diff --git a/backend/src/main/java/com/designhub/service/TaskItemService.java b/backend/src/main/java/com/designhub/service/TaskItemService.java
index 08ad8d5..4638e3e 100644
--- a/backend/src/main/java/com/designhub/service/TaskItemService.java
+++ b/backend/src/main/java/com/designhub/service/TaskItemService.java
@@ -272,6 +272,28 @@ public class TaskItemService {
         }
     }
 
+    /**
+     * 判断用户部门是否属于目标部门（含目标部门的子部门）
+     */
+    private boolean isDeptMatchedOrInherited(Long userDeptId, Long targetDeptId) {
+        if (userDeptId == null || targetDeptId == null) {
+            return false;
+        }
+        Long currentDeptId = userDeptId;
+        while (currentDeptId != null) {
+            if (targetDeptId.equals(currentDeptId)) {
+                return true;
+            }
+            com.designhub.entity.Department currentDept = departmentMapper.selectById(currentDeptId);
+            if (currentDept == null || currentDept.getParentId() == null
+                || currentDeptId.equals(currentDept.getParentId())) {
+                break;
+            }
+            currentDeptId = currentDept.getParentId();
+        }
+        return false;
+    }
+
     /**
      * 获取进行中的子任务列表
      * @param receiverId 接单人ID，null表示不按接单人过滤
@@ -424,8 +446,14 @@ public class TaskItemService {
                 throw new BusinessException(ResultCode.FORBIDDEN, "部门负责人不能接单，请分配给设计师");
             }
 
+            // 检查4：如果子任务已指定接单部门，则仅允许该部门（含子部门）成员接单
+            if (item.getReceiverDeptId() != null
+                && !isDeptMatchedOrInherited(user.getDeptId(), item.getReceiverDeptId())) {
+                throw new BusinessException(ResultCode.FORBIDDEN, "该任务仅允许指定接单部门成员接单");
+            }
+
             // 检查4：验证部门是否允许接该任务类型（支持三级分类继承二级分类的配置，支持子部门继承父部门权限）
-            if (item.getTaskTypeId() != null) {
+            if (item.getReceiverDeptId() == null && item.getTaskTypeId() != null) {
                 com.designhub.entity.DemandType demandType = configService.getDemandTypeById(item.getTaskTypeId());
                 if (demandType != null) {
                     // 获取允许的部门ID（支持任务类型继承）