diff --git a/tests/system-test/2-query/mergeFileSttQuery.py b/tests/system-test/2-query/mergeFileSttQuery.py
index 7d2695a760..4f15fe60f1 100644
--- a/tests/system-test/2-query/mergeFileSttQuery.py
+++ b/tests/system-test/2-query/mergeFileSttQuery.py
@@ -42,18 +42,38 @@ class TDTestCase:
         
     def run(self):
         binPath = self.getPath()
-        tdLog.debug("insert full data block and flush db")
+        tdLog.debug("insert full data block that has first time '2021-10-02 00:00:00.001' and flush db")
         os.system(f"{binPath} -f ./2-query/megeFileSttQuery.json")
         tdSql.execute("flush database db;")
-        tdLog.debug("insert disorder data and flush db")
+        
+        tdLog.debug("insert only a piece of data that is behind the time that already exists and flush db")
+        tdSql.execute("insert into  db.d0 values ('2021-10-01 23:59:59.990',12.793,208,0.84) ;")
+        tdSql.execute("flush database db;")
+        tdLog.debug("check data")
+        sleep(1)
+        tdSql.query("select count(*) from db.d0;")
+        tdSql.checkData(0,0,10001)
+        tdSql.execute("drop database db;")
+
+
+
+
+
+        tdLog.debug("insert full data block that has first time '2021-10-02 00:00:00.001' and flush db")
+        os.system(f"{binPath} -f ./2-query/megeFileSttQuery.json")
+        tdSql.execute("flush database db;")
+        
+        tdLog.debug("insert  four pieces of disorder data, and the time range covers the data file that was previously placed on disk and flush db")
         os.system(f"{binPath} -f ./2-query/megeFileSttQueryUpdate.json")
         tdSql.execute("flush database db;")
         tdLog.debug("check data")
+        tdSql.query("select count(*) from db.d0;",queryTimes=3)
+        tdSql.checkData(0,0,10004)
         tdSql.query("select ts from db.d0 limit 5;")
         tdSql.checkData(0, 0, '2021-10-02 00:00:00.001')
         tdSql.checkData(1, 0, '2021-10-02 00:01:00.000')
-        tdLog.debug("update disorder data and flush db")
 
+        tdLog.debug("update the same disorder data and flush db")
         os.system(f"{binPath} -f ./2-query/megeFileSttQueryUpdate.json")
         tdSql.query("select ts from db.d0 limit 5;")
         tdSql.checkData(0, 0, '2021-10-02 00:00:00.001')