diff --git a/yudao-module-system/src/main/java/cn/iocoder/yudao/module/system/service/permission/PermissionServiceImpl.java b/yudao-module-system/src/main/java/cn/iocoder/yudao/module/system/service/permission/PermissionServiceImpl.java
index 8eb5b09..d88a921 100644
--- a/yudao-module-system/src/main/java/cn/iocoder/yudao/module/system/service/permission/PermissionServiceImpl.java
+++ b/yudao-module-system/src/main/java/cn/iocoder/yudao/module/system/service/permission/PermissionServiceImpl.java
@@ -303,7 +303,7 @@ public class PermissionServiceImpl implements PermissionService {
                 CollUtil.addAll(result.getDeptIds(), role.getDataScopeDeptIds());
                 // 自定义可见部门时，保证可以看到自己所在的部门。否则，一些场景下可能会有问题。
                 // 例如说，登录时，基于 t_user 的 username 查询会可能被 dept_id 过滤掉
-                CollUtil.addAll(result.getDeptIds(), userDeptId.get());
+                CollectionUtils.addIfNotNull(result.getDeptIds(), userDeptId.get());
                 continue;
             }
             // 情况三，DEPT_ONLY
@@ -313,9 +313,14 @@ public class PermissionServiceImpl implements PermissionService {
             }
             // 情况四，DEPT_DEPT_AND_CHILD
             if (Objects.equals(role.getDataScope(), DataScopeEnum.DEPT_AND_CHILD.getScope())) {
-                CollUtil.addAll(result.getDeptIds(), deptService.getChildDeptIdListFromCache(userDeptId.get()));
+                Long deptId = userDeptId.get();
+                // 用户未设置部门，直接跳过；否则 getChildDeptIdListFromCache 走缓存注解会因 null key 报错
+                if (deptId == null) {
+                    continue;
+                }
+                CollUtil.addAll(result.getDeptIds(), deptService.getChildDeptIdListFromCache(deptId));
                 // 添加本身部门编号
-                CollUtil.addAll(result.getDeptIds(), userDeptId.get());
+                result.getDeptIds().add(deptId);
                 continue;
             }
             // 情况五，SELF
diff --git a/yudao-module-system/src/test/java/cn/iocoder/yudao/module/system/service/permission/PermissionServiceTest.java b/yudao-module-system/src/test/java/cn/iocoder/yudao/module/system/service/permission/PermissionServiceTest.java
index 52ba3f9..87f12b7 100644
--- a/yudao-module-system/src/test/java/cn/iocoder/yudao/module/system/service/permission/PermissionServiceTest.java
+++ b/yudao-module-system/src/test/java/cn/iocoder/yudao/module/system/service/permission/PermissionServiceTest.java
@@ -441,6 +441,34 @@ public class PermissionServiceTest extends BaseDbUnitTest {
     }
 
     @Test
+    public void testGetDeptDataPermission_DeptCustom_userDeptIdNull() {
+        try (MockedStatic<SpringUtil> springUtilMockedStatic = mockStatic(SpringUtil.class)) {
+            springUtilMockedStatic.when(() -> SpringUtil.getBean(eq(PermissionServiceImpl.class)))
+                    .thenReturn(permissionService);
+
+            // 准备参数
+            Long userId = 1L;
+            // mock 用户的角色编号
+            userRoleMapper.insert(randomPojo(UserRoleDO.class).setUserId(userId).setRoleId(2L));
+            // mock 获得用户的角色
+            RoleDO roleDO = randomPojo(RoleDO.class, o -> o.setDataScope(DataScopeEnum.DEPT_CUSTOM.getScope())
+                    .setStatus(CommonStatusEnum.ENABLE.getStatus()));
+            when(roleService.getRoleListFromCache(eq(singleton(2L)))).thenReturn(toList(roleDO));
+            // mock 部门的返回：用户未设置部门
+            when(userService.getUser(eq(1L))).thenReturn(new AdminUserDO()); // deptId 为 null
+
+            // 调用
+            DeptDataPermissionRespDTO result = permissionService.getDeptDataPermission(userId);
+            // 断言：角色配置的可见部门仍正常加入，但 null 不进集合
+            assertFalse(result.getAll());
+            assertFalse(result.getSelf());
+            assertEquals(roleDO.getDataScopeDeptIds().size(), result.getDeptIds().size());
+            assertTrue(CollUtil.containsAll(result.getDeptIds(), roleDO.getDataScopeDeptIds()));
+            assertFalse(result.getDeptIds().contains(null));
+        }
+    }
+
+    @Test
     public void testGetDeptDataPermission_DeptOnly() {
         try (MockedStatic<SpringUtil> springUtilMockedStatic = mockStatic(SpringUtil.class)) {
             springUtilMockedStatic.when(() -> SpringUtil.getBean(eq(PermissionServiceImpl.class)))
@@ -501,6 +529,33 @@ public class PermissionServiceTest extends BaseDbUnitTest {
     }
 
     @Test
+    public void testGetDeptDataPermission_DeptAndChild_userDeptIdNull() {
+        try (MockedStatic<SpringUtil> springUtilMockedStatic = mockStatic(SpringUtil.class)) {
+            springUtilMockedStatic.when(() -> SpringUtil.getBean(eq(PermissionServiceImpl.class)))
+                    .thenReturn(permissionService);
+
+            // 准备参数
+            Long userId = 1L;
+            // mock 用户的角色编号
+            userRoleMapper.insert(randomPojo(UserRoleDO.class).setUserId(userId).setRoleId(2L));
+            // mock 获得用户的角色
+            RoleDO roleDO = randomPojo(RoleDO.class, o -> o.setDataScope(DataScopeEnum.DEPT_AND_CHILD.getScope())
+                    .setStatus(CommonStatusEnum.ENABLE.getStatus()));
+            when(roleService.getRoleListFromCache(eq(singleton(2L)))).thenReturn(toList(roleDO));
+            // mock 部门的返回：用户未设置部门
+            when(userService.getUser(eq(1L))).thenReturn(new AdminUserDO()); // deptId 为 null
+
+            // 调用
+            DeptDataPermissionRespDTO result = permissionService.getDeptDataPermission(userId);
+            // 断言：deptId 为 null，整段跳过；deptIds 为空，子部门查询不被触发
+            assertFalse(result.getAll());
+            assertFalse(result.getSelf());
+            assertTrue(CollUtil.isEmpty(result.getDeptIds()));
+            verify(deptService, never()).getChildDeptIdListFromCache(any());
+        }
+    }
+
+    @Test
     public void testGetDeptDataPermission_Self() {
         try (MockedStatic<SpringUtil> springUtilMockedStatic = mockStatic(SpringUtil.class)) {
             springUtilMockedStatic.when(() -> SpringUtil.getBean(eq(PermissionServiceImpl.class)))