diff --git a/backend/app/services/task_service.py b/backend/app/services/task_service.py
index dbf5f13..4db8b17 100644
--- a/backend/app/services/task_service.py
+++ b/backend/app/services/task_service.py
@@ -91,6 +91,37 @@ async def _get_task_with_children_recursive(db: AsyncSession, task_id: uuid.UUID
     return task
 
 
+def _to_flat_response(task: Task) -> TaskResponse:
+    """扁平序列化，不递归 children（避免 MissingGreenlet）"""
+    product_sn = ""
+    product_material = ""
+    try:
+        if task.product:
+            product_sn = task.product.serial_number or ""
+            product_material = (task.product.material_name or task.product.material_id or "")
+    except Exception:
+        pass
+    return TaskResponse(
+        id=task.id,
+        product_id=task.product_id,
+        product_sn=product_sn,
+        product_material=product_material,
+        parent_task_id=task.parent_task_id,
+        task_name=task.task_name,
+        assignee_id=task.assignee_id,
+        status=task.status,
+        notify_parent_on_complete=task.notify_parent_on_complete,
+        is_rework=task.is_rework,
+        remark=task.remark,
+        reject_reason=task.reject_reason,
+        received_at=task.received_at,
+        completed_at=task.completed_at,
+        created_at=task.created_at,
+        child_tasks=[],
+        records=[TaskRecordResponse.model_validate(r) for r in (task.records or [])],
+    )
+
+
 def _to_response(task: Task) -> TaskResponse:
     """将 Task ORM 对象转为递归 TaskResponse"""
     product_sn = ""
@@ -237,9 +268,9 @@ async def get_all_tasks(
     result = await db.execute(stmt)
     tasks = result.scalars().all()
 
-    # 返回所有匹配的任务（含子任务），不再过滤 parent_task_id
-    all_tasks = [_to_response(t) for t in tasks]
-    return TaskListResponse(tasks=all_tasks, total=len(all_tasks))
+    # 返回扁平列表（不递归 children，避免 MissingGreenlet）
+    flat_tasks = [_to_flat_response(t) for t in tasks]
+    return TaskListResponse(tasks=flat_tasks, total=len(flat_tasks))
 
 
 # ============================================================