diff --git a/inventory-backend/app/services/outbound_service.py b/inventory-backend/app/services/outbound_service.py
index d5f518b..faef504 100644
--- a/inventory-backend/app/services/outbound_service.py
+++ b/inventory-backend/app/services/outbound_service.py
@@ -1,6 +1,7 @@
 import uuid  # .material -> .base refactor checked
 from datetime import datetime, timezone, timedelta
 from sqlalchemy import or_, func, desc, and_
+from sqlalchemy.orm import joinedload
 from app.extensions import db
 from app.models.outbound import TransOutbound, OutboundApproval
 
@@ -475,6 +476,37 @@ class OutboundService:
             'stock_product': StockProduct
         }
 
+        # ==========================================
+        # ★ 优化步骤 1：第一遍循环，单纯收集所有的 stock_id
+        # ==========================================
+        stock_ids_by_table = {'stock_buy': set(), 'stock_semi': set(), 'stock_product': set()}
+
+        for d in details:
+            if d.source_table in stock_ids_by_table and d.stock_id:
+                stock_ids_by_table[d.source_table].add(d.stock_id)
+
+        # ==========================================
+        # ★ 优化步骤 2：发起批量查询，并强制 JOIN 基础物料表
+        # ==========================================
+        # 格式: { ('stock_buy', 101): stock_obj, ... }
+        preloaded_stocks = {}
+
+        for table_name, ids in stock_ids_by_table.items():
+            if not ids:
+                continue
+
+            ModelClass = model_map[table_name]
+            # 魔法在这里：in_() 一次性查出所有库存，joinedload 顺便把 base 表的数据一起拉回来
+            items = ModelClass.query.options(
+                joinedload(ModelClass.base)
+            ).filter(ModelClass.id.in_(ids)).all()
+
+            for item in items:
+                preloaded_stocks[(table_name, item.id)] = item
+
+        # ==========================================
+        # ★ 优化步骤 3：第二遍循环，纯内存拼装（极速）
+        # ==========================================
         for d in details:
             ono = d.outbound_no
             if ono not in grouped_map:
@@ -490,34 +522,20 @@ class OutboundService:
                     'items': []
                 }
 
-            # --- 查询物品详细信息 (名称, 规格, 类型, 类别, 批号/SN) ---
-            item_name = "未知物品"
-            item_spec = ""
-            item_cat = ""
-            item_type = ""
-            batch_sn = "-"
+            # --- 直接从内存字典中获取，O(1) 复杂度，绝对不触发 SQL ---
+            item_name, item_spec, item_cat, item_type, batch_sn = "未知物品", "", "", "", "-"
 
-            ModelClass = model_map.get(d.source_table)
-            if ModelClass and d.stock_id:
-                try:
-                    stock_item = ModelClass.query.get(d.stock_id)
-                    if stock_item:
-                        # 获取批号/序列号用于追溯
-                        batch_sn = getattr(stock_item, 'batch_number', None) or getattr(stock_item, 'serial_number', None) or '-'
-                        if stock_item.base:
-                            item_name = stock_item.base.name
-                            item_spec = stock_item.base.spec_model
-                            item_cat = stock_item.base.category
-                            item_type = stock_item.base.material_type
-                        elif stock_item and hasattr(stock_item, 'base_id') and stock_item.base_id:
-                            base_info = MaterialBase.query.get(stock_item.base_id)
-                            if base_info:
-                                item_name = base_info.name
-                                item_spec = base_info.spec_model
-                                item_cat = base_info.category
-                                item_type = base_info.material_type
-                except Exception as e:
-                    print(f"Error fetching detail for stock_id {d.stock_id}: {e}")
+            stock_item = preloaded_stocks.get((d.source_table, d.stock_id))
+
+            if stock_item:
+                batch_sn = getattr(stock_item, 'batch_number', None) or getattr(stock_item, 'serial_number', None) or '-'
+
+                # 因为前面用了 joinedload，这里调用 .base 瞬间返回，不会去查数据库
+                if stock_item.base:
+                    item_name = stock_item.base.name
+                    item_spec = stock_item.base.spec_model
+                    item_cat = stock_item.base.category
+                    item_type = stock_item.base.material_type
 
             # 计算金额
             price = float(d.unit_price) if d.unit_price else 0
diff --git a/inventory-backend/app/services/trans_service.py b/inventory-backend/app/services/trans_service.py
index b4e6327..5edfc3a 100644
--- a/inventory-backend/app/services/trans_service.py
+++ b/inventory-backend/app/services/trans_service.py
@@ -114,12 +114,12 @@ class TransService:
     @staticmethod
     def process_return(data, operator_name):
         """
-        还库逻辑（支持部分归还）：
-        1. 校验本次归还数量不能大于待还数量
-        2. 恢复可用库存（按本次归还数量）
-        3. 更新库位 (如果有变动)
-        4. 记录库管签字
-        5. 更新归还数量和状态（部分归还/全部归还）
+        还库逻辑（支持部分归还）- 已优化，消除 N+1 和长事务死锁风险
+        四步走策略：
+        1. 收集所有 borrow_id
+        2. 批量锁定借用记录
+        3. 收集库存ID并批量锁定库存
+        4. 内存中完成业务逻辑
         """
         items = data.get('items', [])
         signature = data.get('signature_path')  # 库管签字
@@ -130,15 +130,60 @@ class TransService:
         model_map = {'stock_buy': StockBuy, 'stock_semi': StockSemi, 'stock_product': StockProduct}
 
         try:
+            # ==========================================
+            # ★ 优化步骤 1：收集所有 borrow_id
+            # ==========================================
+            borrow_ids = []
+            item_map = {}  # 存储原始 item 数据，key=borrow_id
             for item in items:
                 borrow_id = item.get('id')
-                # 前端传入的本次归还数量
-                return_qty = float(item.get('return_qty', 0))
-                # 前端如果没有填 return_location，应该在提交前处理好，或者这里做 fallback
-                # 这里假设前端传来的 return_location 就是最终要保存的库位
-                final_location = item.get('return_location')
+                if borrow_id:
+                    borrow_ids.append(borrow_id)
+                    item_map[borrow_id] = {
+                        'return_qty': float(item.get('return_qty', 0)),
+                        'final_location': item.get('return_location')
+                    }
 
-                record = TransBorrow.query.with_for_update().get(borrow_id)
+            if not borrow_ids:
+                raise ValueError("没有有效的归还记录")
+
+            # ==========================================
+            # ★ 优化步骤 2：批量锁定借用记录
+            # ==========================================
+            borrow_records = TransBorrow.query.with_for_update().filter(
+                TransBorrow.id.in_(borrow_ids)
+            ).all()
+
+            borrow_map = {r.id: r for r in borrow_records}
+
+            # ==========================================
+            # ★ 优化步骤 3：收集库存ID并批量锁定库存
+            # ==========================================
+            stock_ids_by_table = {'stock_buy': set(), 'stock_semi': set(), 'stock_product': set()}
+
+            for borrow_id, record in borrow_map.items():
+                if record.source_table in stock_ids_by_table and record.stock_id:
+                    stock_ids_by_table[record.source_table].add(record.stock_id)
+
+            stock_map = {}  # 格式: { ('stock_buy', 101): stock_obj }
+            for table_name, ids in stock_ids_by_table.items():
+                if not ids:
+                    continue
+                ModelClass = model_map[table_name]
+                stocks = ModelClass.query.with_for_update().filter(
+                    ModelClass.id.in_(ids)
+                ).all()
+                for stock in stocks:
+                    stock_map[(table_name, stock.id)] = stock
+
+            # ==========================================
+            # ★ 优化步骤 4：内存中完成业务逻辑
+            # ==========================================
+            for borrow_id, item_data in item_map.items():
+                return_qty = item_data['return_qty']
+                final_location = item_data['final_location']
+
+                record = borrow_map.get(borrow_id)
                 if not record:
                     continue
 
@@ -153,22 +198,19 @@ class TransService:
                 if return_qty > pending_qty:
                     raise ValueError(f"本次归还数量({return_qty})不能大于待还数量({pending_qty})")
 
-                ModelClass = model_map.get(record.source_table)
-                if ModelClass:
-                    stock = ModelClass.query.with_for_update().get(record.stock_id)
-                    if stock:
-                        # 1. 恢复可用库存（按本次归还数量）
-                        stock.available_quantity = float(stock.available_quantity) + return_qty
+                # 更新库存
+                stock = stock_map.get((record.source_table, record.stock_id))
+                if stock:
+                    # 恢复可用库存
+                    stock.available_quantity = float(stock.available_quantity) + return_qty
+                    # 更新库位
+                    if final_location:
+                        stock.warehouse_location = final_location
 
-                        # 2. 更新库位 (如果提供了有效值)
-                        if final_location:
-                            stock.warehouse_location = final_location
-
-                # 3. 更新归还数量
+                # 更新归还数量和状态
                 new_returned_qty = returned_qty + return_qty
                 record.returned_quantity = new_returned_qty
 
-                # 4. 更新状态
                 if new_returned_qty >= total_qty:
                     record.is_returned = True
                     record.status = 'returned'