diff --git a/services/ans/src/advanced_notification_service.cpp b/services/ans/src/advanced_notification_service.cpp
index 443c4d12426fe4966875185e03364699ee7cf11f..7b33b5aefbca3d7f360436c5349ea9035ce1bdee 100644
--- a/services/ans/src/advanced_notification_service.cpp
+++ b/services/ans/src/advanced_notification_service.cpp
@@ -1360,6 +1360,11 @@ ErrCode AdvancedNotificationService::Subscribe(
 
     ErrCode errCode = ERR_OK;
     do {
+        if (subscriber == nullptr) {
+            errCode = ERR_ANS_INVALID_PARAM;
+            break;
+        }
+
         bool isSubsystem = AccessTokenHelper::VerifyNativeToken(IPCSkeleton::GetCallingTokenID());
         if (!IsSystemApp() && !isSubsystem) {
             ANS_LOGE("Client is not a system app or subsystem");
@@ -1372,11 +1377,6 @@ ErrCode AdvancedNotificationService::Subscribe(
             break;
         }
 
-        if (subscriber == nullptr) {
-            errCode = ERR_ANS_INVALID_PARAM;
-            break;
-        }
-
         errCode = NotificationSubscriberManager::GetInstance()->AddSubscriber(subscriber, info);
         if (errCode != ERR_OK) {
             break;
@@ -1393,6 +1393,8 @@ ErrCode AdvancedNotificationService::Unsubscribe(
     HITRACE_METER_NAME(HITRACE_TAG_NOTIFICATION, __PRETTY_FUNCTION__);
     ANS_LOGD("%{public}s", __FUNCTION__);
 
+    SendUnSubscribeHiSysEvent(IPCSkeleton::GetCallingPid(), IPCSkeleton::GetCallingUid(), info);
+
     bool isSubsystem = AccessTokenHelper::VerifyNativeToken(IPCSkeleton::GetCallingTokenID());
     if (!IsSystemApp() && !isSubsystem) {
         ANS_LOGE("Client is not a system app or subsystem");
@@ -1412,7 +1414,6 @@ ErrCode AdvancedNotificationService::Unsubscribe(
         return errCode;
     }
 
-    SendUnSubscribeHiSysEvent(IPCSkeleton::GetCallingPid(), IPCSkeleton::GetCallingUid(), info);
     return ERR_OK;
 }