diff --git a/merchant_ops/services/authz.py b/merchant_ops/services/authz.py
index 63f3676..d4db512 100644
--- a/merchant_ops/services/authz.py
+++ b/merchant_ops/services/authz.py
@@ -33,9 +33,7 @@ def get_active_staff_member(user):
 
 
 def require_active_staff_member(user):
-    """子客服接口鉴权：区分老板误入、未绑定、禁用、移除等场景。"""
-    if is_merchant_owner(user):
-        raise StaffAuthError(403, '您是商家老板，请使用商家端原接口')
+    """子客服接口鉴权：区分未绑定、禁用、移除等场景（已是商家老板也可担任其他店子客服）。"""
     member = MerchantStaffMember.query.filter(
         staff_user_id=user.UserUID,
     ).select_related('role').order_by('-id').first()
@@ -132,9 +130,21 @@ def resolve_owner_or_staff(request, perm_code=None):
     return 'staff', member.merchant_id, member, user.UserUID
 
 
-def assert_not_merchant_when_bind(user):
-    if is_merchant_owner(user):
-        raise StaffAuthError(403, '您已是商家，无法成为子客服')
+def assert_not_self_merchant_when_bind(user, invite_merchant_id):
+    """不能绑定为自己店铺的客服；可以是其他商家的子客服。"""
+    if invite_merchant_id is not None and str(user.UserUID) == str(invite_merchant_id):
+        raise StaffAuthError(403, '不能绑定为自己商家的客服')
+
+
+def assert_can_bind_staff(user, invite_merchant_id=None):
+    assert_not_self_merchant_when_bind(user, invite_merchant_id)
+    existing = MerchantStaffMember.query.filter(
+        staff_user_id=user.UserUID, status=MEMBER_STATUS_ACTIVE
+    ).first()
+    if existing:
+        if invite_merchant_id and str(existing.merchant_id) == str(invite_merchant_id):
+            raise StaffAuthError(400, '您已是该商家客服')
+        raise StaffAuthError(403, '您已绑定其他商家客服，请先联系原商家解除后再绑定')
 
 
 def assert_no_active_staff_when_merchant_register(user):
@@ -144,14 +154,6 @@ def assert_no_active_staff_when_merchant_register(user):
         raise StaffAuthError(403, '您当前是商家客服，请先联系商家解除后再认证商家')
 
 
-def assert_can_bind_staff(user):
-    assert_not_merchant_when_bind(user)
-    if MerchantStaffMember.query.filter(
-        staff_user_id=user.UserUID, status=MEMBER_STATUS_ACTIVE
-    ).exists():
-        raise StaffAuthError(403, '您已绑定商家客服，无法重复绑定')
-
-
 def get_owner_permissions():
     return list(OWNER_ALL_PERMISSIONS)
 
diff --git a/merchant_ops/views_staff.py b/merchant_ops/views_staff.py
index 0349376..8992918 100644
--- a/merchant_ops/views_staff.py
+++ b/merchant_ops/views_staff.py
@@ -35,7 +35,6 @@ class StaffBindView(APIView):
 
     def post(self, request):
         try:
-            assert_can_bind_staff(request.user)
             invite_code = str(request.data.get('inviteCode') or request.data.get('invite_code') or '').strip()
             if not invite_code or invite_code == 'XQKF2026':
                 return Response({'code': 400, 'msg': '请使用商家提供的一次性邀请码', 'data': None})
@@ -44,6 +43,7 @@ class StaffBindView(APIView):
                 inv = MerchantStaffInvite.objects.select_for_update().get(
                     invite_code=invite_code, status=INVITE_STATUS_UNUSED,
                 )
+                assert_can_bind_staff(request.user, invite_merchant_id=inv.merchant_id)
                 if inv.expire_at and inv.expire_at < timezone.now():
                     inv.status = 3
                     inv.save(update_fields=['status'])