diff --git a/source/libs/stream/src/streamExec.c b/source/libs/stream/src/streamExec.c
index 621a4b57c7..1af442182e 100644
--- a/source/libs/stream/src/streamExec.c
+++ b/source/libs/stream/src/streamExec.c
@@ -423,16 +423,17 @@ int32_t streamExecForAll(SStreamTask* pTask) {
     }
 
     if (pTask->info.taskLevel == TASK_LEVEL__SINK) {
+      ASSERT(pInput->type == STREAM_INPUT__DATA_BLOCK || pInput->type == STREAM_INPUT__CHECKPOINT);
+
       if (pInput->type == STREAM_INPUT__DATA_BLOCK) {
         qDebug("s-task:%s sink task start to sink %d blocks", id, batchSize);
         streamTaskOutputResultBlock(pTask, (SStreamDataBlock*)pInput);
         continue;
+      } else {  // for sink task, do nothing.
+        ASSERT(pTask->status.taskStatus == TASK_STATUS__CK);
+        pTask->status.taskStatus = TASK_STATUS__CK_READY;
+        return 0;
       }
-    } else {
-      ASSERT(pInput->type == STREAM_INPUT__CHECKPOINT);
-      ASSERT(pTask->status.taskStatus == TASK_STATUS__CK);
-      pTask->status.taskStatus = TASK_STATUS__CK_READY;
-      return 0;
     }
 
     int64_t st = taosGetTimestampMs();