diff --git a/inventory-backend/app/api/v1/transactions.py b/inventory-backend/app/api/v1/transactions.py
index cced585..44c795c 100644
--- a/inventory-backend/app/api/v1/transactions.py
+++ b/inventory-backend/app/api/v1/transactions.py
@@ -3,6 +3,7 @@ from flask_jwt_extended import jwt_required, get_jwt_identity, get_jwt
 from app.utils.decorators import permission_required, audit_log
 from app.services.auth_service import AuthService
 from app.services.trans_service import TransService
+from app.services.borrow_service import BorrowApprovalService
 import traceback
 
 trans_bp = Blueprint('transactions', __name__, url_prefix='/transactions')
@@ -29,6 +30,16 @@ def get_current_user_permissions():
     return perms
 
 
+def get_current_user_info():
+    """获取当前用户信息和角色"""
+    from app.models.system import SysUser
+    identity = get_jwt_identity()
+    if not identity:
+        return None, None
+    user = SysUser.query.get(identity)
+    return user.id if user else None, user.role if user else None
+
+
 def filter_item_by_permissions(item_dict, user_permissions, prefix='op_records'):
     """
     根据用户权限过滤 item 字典，无权限的字段值置为 None
@@ -125,3 +136,178 @@ def get_records():
     if res.get('items'):
         res['items'] = [filter_item_by_permissions(item, user_permissions, 'op_records') for item in res['items']]
     return jsonify({'code': 200, 'data': res})
+
+
+# ==============================================================================
+# 借库审批流 API（与出库审批流平行）
+# ==============================================================================
+
+# --- 提交借库申请 ---
+@trans_bp.route('/borrow/request', methods=['POST'])
+@jwt_required()
+def submit_borrow_request():
+    """
+    提交借库申请（仅存储意向，不扣库存）
+    请求体: { items: [...], allowed_approvers: [...], remark: '', approver_id: int }
+    """
+    try:
+        user_id, user_role = get_current_user_info()
+        if not user_id:
+            return jsonify({'code': 401, 'msg': '用户未登录'}), 401
+
+        from app.models.system import SysUser
+        current_user = SysUser.query.get(user_id)
+        current_username = current_user.username if current_user else None
+
+        data = request.get_json() or {}
+        items = data.get('items', [])
+        if not items:
+            return jsonify({'code': 400, 'msg': '借库物品列表不能为空'}), 400
+
+        required_fields = ['name', 'spec_model', 'quantity']
+        for idx, item in enumerate(items):
+            missing = [f for f in required_fields if f not in item or str(item.get(f) or '').strip() == '']
+            if missing:
+                return jsonify({
+                    'code': 400,
+                    'msg': f'第{idx + 1}条物品缺少必填字段: {", ".join(missing)}'
+                }), 400
+            try:
+                qty = float(item.get('quantity', 0))
+                if qty <= 0:
+                    return jsonify({'code': 400, 'msg': f'第{idx + 1}条物品的借库数量必须大于0'}), 400
+            except (TypeError, ValueError):
+                return jsonify({'code': 400, 'msg': f'第{idx + 1}条物品的 quantity 格式无效'}), 400
+
+        approver_id = data.get('approver_id')
+        _default_approvers = [
+            {"type": "role", "value": "SUPERVISOR"},
+            {"type": "role", "value": "SUPER_ADMIN"}
+        ]
+        allowed_approvers = data.get('allowed_approvers') or _default_approvers
+
+        approval = BorrowApprovalService.submit_approval(
+            applicant_id=user_id,
+            items=items,
+            allowed_approvers=allowed_approvers,
+            remark=data.get('remark'),
+            approver_id=approver_id,
+            borrower_name=current_username
+        )
+
+        return jsonify({'code': 200, 'msg': '借库申请已提交', 'data': approval.to_dict()}), 200
+
+    except ValueError as e:
+        return jsonify({'code': 400, 'msg': str(e)}), 400
+    except Exception as e:
+        return jsonify({'code': 500, 'msg': f"接口内部报错: {str(e)}", 'trace': traceback.format_exc()}), 500
+
+
+# --- 审批借库申请 ---
+@trans_bp.route('/borrow/request/<int:request_id>/approve', methods=['PATCH'])
+@jwt_required()
+def approve_borrow_request(request_id):
+    """
+    审批借库申请
+    请求体: {"action": "approve" | "reject", "reject_reason": "驳回原因"}
+    """
+    try:
+        user_id, user_role = get_current_user_info()
+        if not user_id:
+            return jsonify({'code': 401, 'msg': '用户未登录'}), 401
+
+        data = request.get_json() or {}
+        action = data.get('action', 'approve')
+        reject_reason = data.get('reject_reason')
+
+        if action not in ('approve', 'reject'):
+            return jsonify({'code': 400, 'msg': '无效的审批操作，仅支持 approve 或 reject'}), 400
+
+        if action == 'reject' and not reject_reason:
+            return jsonify({'code': 400, 'msg': '驳回时必须提供原因'}), 400
+
+        success, message, approval = BorrowApprovalService.approve(
+            request_id=request_id,
+            user_id=user_id,
+            user_role=user_role,
+            action=action,
+            reject_reason=reject_reason
+        )
+
+        if not success:
+            return jsonify({'code': 400, 'msg': message}), 400
+
+        return jsonify({'code': 200, 'msg': message, 'data': approval.to_dict() if approval else None}), 200
+
+    except Exception as e:
+        traceback.print_exc()
+        return jsonify({'code': 500, 'msg': f'服务器内部错误: {str(e)}'}), 500
+
+
+# --- 获取借库审批单列表 ---
+@trans_bp.route('/borrow/request', methods=['GET'])
+@jwt_required()
+def get_borrow_request_list():
+    """
+    获取借库审批单列表
+    Query参数: page, limit, applicant_id, status
+    """
+    try:
+        page = int(request.args.get('page', 1))
+        limit = int(request.args.get('limit', 10))
+        applicant_id = request.args.get('applicant_id')
+        if applicant_id:
+            applicant_id = int(applicant_id)
+        status = request.args.get('status')
+        if status is not None:
+            status = int(status)
+
+        result = BorrowApprovalService.get_request_list(
+            page=page, per_page=limit, applicant_id=applicant_id, status=status
+        )
+
+        return jsonify({'code': 200, 'msg': '获取成功', 'data': result}), 200
+
+    except Exception as e:
+        return jsonify({'code': 500, 'msg': str(e)}), 500
+
+
+# --- 执行借库扣减（审批通过后调用）---
+@trans_bp.route('/borrow/dispatch', methods=['POST'])
+@jwt_required()
+@permission_required('op_borrow:operation')
+def dispatch_borrow():
+    """
+    执行借库扣减
+    请求体: {
+        approval_id: int,   // 关联的审批单ID
+        items: [...],       // 扫码选中的库存物品（含 id, source_table, out_quantity）
+        borrower_name: str,
+        signature_path: str,
+        remark: str,
+        expected_return_time: str
+    }
+    """
+    try:
+        data = request.get_json() or {}
+        approval_id = data.get('approval_id')
+        if not approval_id:
+            return jsonify({'code': 400, 'msg': '缺少 approval_id'}), 400
+
+        borrow_no = TransService.execute_dispatch(
+            approval_id=approval_id,
+            items=data.get('items', []),
+            operator_name=get_jwt_identity(),
+            borrower_name=data.get('borrower_name'),
+            signature=data.get('signature_path'),
+            remark=data.get('remark'),
+            expected_return_time=data.get('expected_return_time')
+        )
+
+        return jsonify({'code': 200, 'msg': '借库成功', 'data': {'borrow_no': borrow_no}}), 200
+
+    except ValueError as e:
+        return jsonify({'code': 400, 'msg': str(e)}), 400
+    except Exception as e:
+        traceback.print_exc()
+        return jsonify({'code': 500, 'msg': f'服务器内部错误: {str(e)}'}), 500
diff --git a/inventory-backend/app/services/borrow_service.py b/inventory-backend/app/services/borrow_service.py
new file mode 100644
index 0000000..61dfcac
--- /dev/null
+++ b/inventory-backend/app/services/borrow_service.py
@@ -0,0 +1,396 @@
+from datetime import datetime
+import pytz
+from app.extensions import db
+from app.models.borrow import BorrowApproval
+from app.models.system import SysUser
+
+
+class BorrowApprovalService:
+    """借库审批服务"""
+
+    @staticmethod
+    def generate_request_no():
+        """
+        生成审批单号: APR-BOR-yyyyMMdd-HHmm-当日流水(4位)
+        """
+        beijing_tz = pytz.timezone('Asia/Shanghai')
+        now = datetime.now(beijing_tz)
+
+        date_str = now.strftime('%Y%m%d')
+        time_str = now.strftime('%H%M')
+
+        prefix = f"APR-BOR-{date_str}-"
+
+        latest = db.session.query(BorrowApproval.request_no).filter(
+            BorrowApproval.request_no.like(f"{prefix}%")
+        ).order_by(BorrowApproval.id.desc()).first()
+
+        if latest:
+            last_seq = int(latest[0].split('-')[-1])
+            sequence = last_seq + 1
+        else:
+            sequence = 1
+
+        return f"APR-BOR-{date_str}-{time_str}-{sequence:04d}"
+
+    @staticmethod
+    def submit_approval(applicant_id, items, allowed_approvers, remark=None, approver_id=None,
+                         borrower_name=None):
+        """
+        提交借库申请（仅存储意向，不扣库存）
+
+        Args:
+            applicant_id: 申请人ID
+            items: 借库物品明细列表，每个物品应包含:
+                - name: 物料名称 (必填)
+                - spec_model: 规格型号 (必填)
+                - quantity: 计划借库数量 (必填)
+                - warehouse_location: 库位 (可选)
+                - remark: 物品备注 (可选)
+            allowed_approvers: 允许审批的人员/角色列表
+            approver_id: 指定审批人ID（可选）
+            remark: 申请说明
+            borrower_name: 借库人姓名（必填）
+
+        Returns:
+            BorrowApproval 实例
+
+        Raises:
+            ValueError: 当 items 为空或缺少必填字段时抛出
+        """
+        if not items:
+            raise ValueError("借库物品列表不能为空")
+
+        required_fields = ['name', 'spec_model', 'quantity']
+        for idx, item in enumerate(items):
+            missing_fields = [f for f in required_fields if f not in item or str(item.get(f) or '').strip() == '']
+            if missing_fields:
+                raise ValueError(
+                    f"第 {idx + 1} 条物品缺少必填字段: {', '.join(missing_fields)}。"
+                    f"必须包含: name, spec_model, quantity"
+                )
+            try:
+                qty = float(item.get('quantity', 0))
+                if qty <= 0:
+                    raise ValueError(f"第 {idx + 1} 条物品的借库数量必须大于0")
+            except (TypeError, ValueError) as e:
+                raise ValueError(f"第 {idx + 1} 条物品的 quantity 格式无效: {str(e)}")
+
+        if not allowed_approvers:
+            raise ValueError("必须指定至少一位审批人")
+
+        if approver_id:
+            allowed_approvers = [{"type": "user", "value": int(approver_id)}]
+
+        request_no = BorrowApprovalService.generate_request_no()
+
+        approval = BorrowApproval(
+            request_no=request_no,
+            applicant_id=applicant_id,
+            remark=remark,
+            borrower_name=borrower_name,
+            status=0,  # 待审批
+        )
+
+        approval.set_items(items)
+        approval.set_allowed_approvers(allowed_approvers)
+
+        db.session.add(approval)
+        db.session.commit()
+
+        # ★ 创建成功后，发送邮件通知审批人（静默处理，不阻断主流程）
+        BorrowApprovalService._notify_new_request(approval, applicant_id, approver_id=approver_id)
+
+        return approval
+
+    @staticmethod
+    def _get_emails_by_identifiers(applicant_id=None, role_codes=None):
+        """
+        根据用户ID或角色列表查询邮箱地址
+
+        Args:
+            applicant_id: 用户ID (按 SysUser.id 查找)
+            role_codes:    角色代码列表，如 ['SUPERVISOR', 'SUPER_ADMIN']
+
+        Returns:
+            去重后的邮箱地址列表
+        """
+        emails = []
+
+        if applicant_id:
+            user = SysUser.query.get(int(applicant_id))
+            if user and user.email:
+                emails.append(user.email)
+
+        if role_codes:
+            for code in role_codes:
+                users = SysUser.query.filter_by(role=code).all()
+                for u in users:
+                    if u.email:
+                        emails.append(u.email)
+
+        return list(set(emails))
+
+    @staticmethod
+    def _notify_new_request(approval, applicant_id, approver_id=None):
+        """发送新借库申请通知邮件给审批人和申请人（静默处理，不阻断主流程）"""
+        try:
+            from flask import current_app
+            from app.utils.email_service import send_new_request_notify
+            from app.models.system import SysUser
+
+            applicant_name = ''
+            applicant_emails = []
+
+            # 1. 收集申请人信息
+            if applicant_id:
+                user = SysUser.query.get(int(applicant_id))
+                if user and user.email:
+                    applicant_emails.append(user.email)
+                    applicant_name = str(user.username).split('/')[0] if '/' in (user.username or '') else (user.username or str(applicant_id))
+
+            # 2. 收集审批人信息
+            approver_emails = []
+            if approver_id:
+                user = SysUser.query.get(int(approver_id))
+                if user and user.email:
+                    approver_emails.append(user.email)
+            else:
+                # 兜底：按角色查询
+                approvers = approval.get_allowed_approvers()
+                role_codes = []
+                for a in approvers:
+                    if a.get('type') == 'role':
+                        role_codes.append(a.get('value', ''))
+                approver_emails = BorrowApprovalService._get_emails_by_identifiers(role_codes=role_codes)
+
+            # 去重
+            all_emails = list(set(applicant_emails + approver_emails))
+            if not all_emails:
+                current_app.logger.info(f"[Email] 借库审批单 {approval.request_no} 无收件人邮箱，跳过通知")
+                return
+
+            # 3. 获取物料明细
+            items = approval.get_items()
+
+            # 4. 分别发送邮件
+            if applicant_emails:
+                try:
+                    send_new_request_notify(
+                        to_emails=applicant_emails,
+                        request_no=approval.request_no,
+                        applicant_name=applicant_name,
+                        remark=f"您的借库申请已提交，等待审批。{approval.remark or ''}",
+                        items=items,
+                        is_applicant_notify=True
+                    )
+                except Exception as e:
+                    current_app.logger.error(f"[Email] 通知申请人失败: {e}")
+
+            if approver_emails:
+                try:
+                    send_new_request_notify(
+                        to_emails=approver_emails,
+                        request_no=approval.request_no,
+                        applicant_name=applicant_name,
+                        remark=approval.remark or '',
+                        items=items,
+                        is_applicant_notify=False
+                    )
+                except Exception as e:
+                    current_app.logger.error(f"[Email] 通知审批人失败: {e}")
+
+        except Exception as e:
+            try:
+                from flask import current_app
+                current_app.logger.error(f"[Email] 发送新借库申请通知邮件失败: {e}")
+            except RuntimeError:
+                import traceback
+                traceback.print_exc()
+
+    @staticmethod
+    def _notify_approval_result(approval, approver_id, action):
+        """发送借库审批结果通知邮件（静默处理，不阻断主流程）"""
+        import logging
+        logger = logging.getLogger(__name__)
+
+        try:
+            from app.utils.email_service import send_approval_result_notify, send_warehouse_dispatch_notify
+            from app.models.system import SysUser as SU
+
+            # 1. 提取申请人信息
+            applicant_name = ''
+            applicant_emails = []
+            if approval.applicant_id:
+                user = SU.query.get(approval.applicant_id)
+                if user:
+                    applicant_name = str(user.username).split('/')[0] if '/' in (user.username or '') else (user.username or '')
+                    if user.email:
+                        applicant_emails.append(user.email)
+
+            # 2. 提取物料明细
+            items = approval.items_json if approval.items_json else []
+
+            # 3. 分支逻辑
+            if action == 'approve':
+                # 3.1 通知库管（带明细）
+                warehouse_role_codes = ['WAREHOUSE_MGR', 'OUTBOUND']
+                warehouse_emails = BorrowApprovalService._get_emails_by_identifiers(role_codes=warehouse_role_codes)
+
+                if warehouse_emails:
+                    try:
+                        send_warehouse_dispatch_notify(
+                            to_emails=warehouse_emails,
+                            request_no=approval.request_no,
+                            applicant_name=applicant_name,
+                            items=items
+                        )
+                    except Exception as e:
+                        logger.error(f"[Email] 通知库管失败: {e}")
+
+                # 3.2 通知申请人（审批通过，带完整物料清单）
+                if applicant_emails:
+                    try:
+                        send_warehouse_dispatch_notify(
+                            to_emails=applicant_emails,
+                            request_no=approval.request_no,
+                            applicant_name=applicant_name,
+                            items=items
+                        )
+                    except Exception as e:
+                        logger.error(f"[Email] 通知申请人（通过）失败: {e}")
+
+            elif action == 'reject':
+                # 3.3 通知申请人（已驳回）
+                if applicant_emails:
+                    try:
+                        send_approval_result_notify(
+                            to_emails=applicant_emails,
+                            request_no=approval.request_no,
+                            is_passed=False,
+                            reject_reason=approval.reject_reason or '未说明原因',
+                            applicant_name=applicant_name
+                        )
+                    except Exception as e:
+                        logger.error(f"[Email] 通知申请人驳回失败: {e}")
+                else:
+                    logger.warning("[Email] 申请人无邮箱，无法发送驳回通知")
+
+        except Exception as e:
+            import traceback
+            traceback.print_exc()
+            logger.error(f"[Email] 外层发送异常: {e}")
+
+    @staticmethod
+    def can_approve(approval, user_id, user_role):
+        """
+        检查用户是否有权限审批
+        """
+        approvers = approval.get_allowed_approvers()
+
+        if user_role and user_role.upper() == 'SUPER_ADMIN':
+            return True
+
+        for approver in approvers:
+            approver_type = approver.get('type', '')
+            approver_value = approver.get('value', '')
+
+            if approver_type == 'user' and str(approver_value) == str(user_id):
+                return True
+
+            if approver_type == 'role' and approver_value == user_role:
+                return True
+
+        return False
+
+    @staticmethod
+    def approve(request_id, user_id, user_role, action='approve', reject_reason=None):
+        """
+        执行审批操作
+
+        Returns:
+            (success: bool, message: str, approval: BorrowApproval or None)
+        """
+        beijing_tz = pytz.timezone('Asia/Shanghai')
+        current_time = datetime.now(beijing_tz).replace(tzinfo=None)
+
+        approval = BorrowApproval.query.get(request_id)
+        if not approval:
+            return False, "审批单不存在", None
+
+        if approval.status != 0:
+            return False, f"审批单状态已更新，无法重复审批 (当前状态: {approval.status})", None
+
+        if not BorrowApprovalService.can_approve(approval, user_id, user_role):
+            return False, "您没有审批此单的权限", None
+
+        try:
+            if action == 'approve':
+                approval.status = 1  # 已通过
+                approval.actual_approver_id = user_id
+                approval.approved_at = current_time
+            elif action == 'reject':
+                approval.status = 2  # 已驳回
+                approval.reject_reason = reject_reason
+            else:
+                return False, "无效的审批操作", None
+
+            db.session.commit()
+
+            # ★ 审批后，发送邮件通知（静默处理，不阻断主流程）
+            BorrowApprovalService._notify_approval_result(approval, user_id, action)
+
+            return True, "审批成功", approval
+
+        except Exception as e:
+            db.session.rollback()
+            return False, f"审批失败: {str(e)}", None
+
+    @staticmethod
+    def get_request_list(page=1, per_page=10, applicant_id=None, status=None):
+        """
+        获取审批单列表
+        """
+        from sqlalchemy import desc
+
+        query = BorrowApproval.query
+
+        if applicant_id:
+            query = query.filter(BorrowApproval.applicant_id == applicant_id)
+
+        if status is not None:
+            query = query.filter(BorrowApproval.status == status)
+
+        query = query.order_by(desc(BorrowApproval.created_at))
+
+        pagination = query.paginate(page=page, per_page=per_page, error_out=False)
+
+        return {
+            'items': [item.to_dict() for item in pagination.items],
+            'total': pagination.total,
+            'pages': pagination.pages,
+            'current_page': page
+        }
+
+    @staticmethod
+    def get_request_by_id(request_id):
+        """根据ID获取审批单"""
+        return BorrowApproval.query.get(request_id)
+
+    @staticmethod
+    def mark_completed(request_id):
+        """标记审批单为已完成（借库执行完成后调用）"""
+        approval = BorrowApproval.query.get(request_id)
+        if not approval:
+            return False, "审批单不存在", None
+
+        if approval.status != 1:
+            return False, f"只有已通过的审批单才能标记为完成 (当前状态: {approval.status})", None
+
+        try:
+            approval.status = 3  # 已完成
+            db.session.commit()
+            return True, "审批单已完成", approval
+        except Exception as e:
+            db.session.rollback()
+            return False, f"操作失败: {str(e)}", None
\ No newline at end of file