diff --git a/src/kit/taosdemo/taosdemo.c b/src/kit/taosdemo/taosdemo.c
index ae36bff81dcd2f8a9825fe0c599f9c70acb58c3b..ce88ba5befd2bf6641c102fa32a245a58b796fed 100644
--- a/src/kit/taosdemo/taosdemo.c
+++ b/src/kit/taosdemo/taosdemo.c
@@ -1116,7 +1116,7 @@ static int printfInsertMeta() {
       if (g_Dbs.db[i].superTbls[j].childTblLimit > 0) {
         printf("      childTblLimit:     \033[33m%d\033[0m\n",  g_Dbs.db[i].superTbls[j].childTblLimit);
       }
-      if (g_Dbs.db[i].superTbls[j].childTblOffset > 0) {
+      if (g_Dbs.db[i].superTbls[j].childTblOffset >= 0) {
         printf("      childTblOffset:    \033[33m%d\033[0m\n",  g_Dbs.db[i].superTbls[j].childTblOffset);
       }
       printf("      insertRows:        \033[33m%"PRId64"\033[0m\n", g_Dbs.db[i].superTbls[j].insertRows);
@@ -2103,6 +2103,12 @@ static int getSuperTableFromServer(TAOS * taos, char* dbName,
 
   if (TBL_ALREADY_EXISTS == superTbls->childTblExists) {
     //get all child table name use cmd: select tbname from superTblName;  
+    int childTblCount = 10000;
+    superTbls->childTblName = (char*)calloc(1, childTblCount * TSDB_TABLE_NAME_LEN);
+    if (superTbls->childTblName == NULL) {
+      fprintf(stderr, "alloc memory failed!");
+      return -1;
+    }
     getAllChildNameOfSuperTable(taos, dbName,
             superTbls->sTblName,
             &superTbls->childTblName,
@@ -2680,6 +2686,7 @@ static int readSampleFromCsvFileToMem(
       return -1;
   }
 
+  assert(superTblInfo->sampleDataBuf);
   memset(superTblInfo->sampleDataBuf, 0,
           MAX_SAMPLES_ONCE_FROM_FILE * superTblInfo->lenOfOneRow);
   while (1) {
@@ -3938,6 +3945,7 @@ static int getRowDataFromSample(char*  dataBuf, int maxLen, int64_t timestamp,
     int ret = readSampleFromCsvFileToMem(superTblInfo);
     if (0 != ret) {
       tmfree(superTblInfo->sampleDataBuf);
+      superTblInfo->sampleDataBuf = NULL;
       return -1;
     }
     *sampleUsePos = 0;
@@ -4324,15 +4332,15 @@ static int prepareSampleDataForSTable(SSuperTable *superTblInfo) {
       return -1;
     }
 
+    superTblInfo->sampleDataBuf = sampleDataBuf;
     int ret = readSampleFromCsvFileToMem(superTblInfo);
     if (0 != ret) {
       tmfree(sampleDataBuf);
+      superTblInfo->sampleDataBuf = NULL;
       return -1;
     }
   }
 
-  superTblInfo->sampleDataBuf = sampleDataBuf;
-
   return 0;
 }
 
@@ -4571,6 +4579,7 @@ static void* syncWrite(void *sarg) {
     if (superTblInfo->numberOfTblInOneSql > 0) {
       syncWriteForNumberOfTblInOneSql(winfo, superTblInfo->sampleDataBuf);
       tmfree(superTblInfo->sampleDataBuf);
+      superTblInfo->sampleDataBuf = NULL;
       return NULL;
     }
   }
@@ -4659,8 +4668,10 @@ static void* syncWrite(void *sarg) {
 
 free_and_statistics_2:
   tmfree(buffer);
-  if (superTblInfo)
+  if (superTblInfo) {
     tmfree(superTblInfo->sampleDataBuf);
+    superTblInfo->sampleDataBuf = NULL;
+  }
 
   printf("====thread[%d] completed total inserted rows: %"PRId64 ", total affected rows: %"PRId64 "====\n", 
           winfo->threadID, 
@@ -4759,13 +4770,18 @@ static void startMultiThreadInsertData(int threads, char* db_name,
     memset(infos, 0, threads * sizeof(threadInfo));
 
     int ntables = 0;
-    if (superTblInfo)
-        if (superTblInfo->childTblOffset)
+    if (superTblInfo) {
+
+        if ((superTblInfo->childTblOffset >= 0) 
+            && (superTblInfo->childTblLimit > 0)) {
+
             ntables = superTblInfo->childTblLimit;
-        else
+        } else {
             ntables = superTblInfo->childTblCount;
-    else
+        }
+    } else {
         ntables = g_args.num_of_tables;
+    }
 
     int a = ntables / threads;
     if (a < 1) {
@@ -4821,7 +4837,7 @@ static void startMultiThreadInsertData(int threads, char* db_name,
  
   int last;
 
-  if ((superTblInfo) && (superTblInfo->childTblOffset))
+  if ((superTblInfo) && (superTblInfo->childTblOffset >= 0))
       last = superTblInfo->childTblOffset;
   else
       last = 0;
diff --git a/tests/pytest/tools/insert-tblimit-tboffset0.json b/tests/pytest/tools/insert-tblimit-tboffset0.json
new file mode 100644
index 0000000000000000000000000000000000000000..302744cab933297d8455aed9c45210385f1ec56f
--- /dev/null
+++ b/tests/pytest/tools/insert-tblimit-tboffset0.json
@@ -0,0 +1,60 @@
+{
+    "filetype": "insert",
+    "cfgdir": "/etc/taos",
+    "host": "127.0.0.1",
+    "port": 6030,
+    "user": "root",
+    "password": "taosdata",
+    "thread_count": 4,
+    "thread_count_create_tbl": 4,
+    "result_file": "./insert_res.txt",
+    "confirm_parameter_prompt": "no",
+    "insert_interval": 0,
+    "num_of_records_per_req": 100,
+    "max_sql_len": 1024000,
+    "databases": [{
+        "dbinfo": {
+            "name": "db",
+            "drop": "yes",
+            "replica": 1,
+            "days": 10,
+            "cache": 16,
+            "blocks": 8,
+            "precision": "ms",
+            "keep": 365,
+            "minRows": 100,
+            "maxRows": 4096,
+            "comp":2,
+            "walLevel":1,
+            "cachelast":0,
+            "quorum":1,
+            "fsync":3000,
+            "update": 0
+        },
+        "super_tables": [{
+            "name": "stb",
+            "child_table_exists":"no",
+            "childtable_count": 100,
+            "childtable_prefix": "stb_",
+            "auto_create_table": "no",
+            "data_source": "rand",
+            "insert_mode": "taosc",
+            "insert_rows": 1000,
+            "childtable_limit": 20,
+            "childtable_offset": 0,
+            "multi_thread_write_one_tbl": "no",
+            "number_of_tbl_in_one_sql": 0,
+            "rows_per_tbl": 100,
+            "max_sql_len": 1024000,
+            "disorder_ratio": 0,
+            "disorder_range": 1000,
+            "timestamp_step": 1,
+            "start_timestamp": "2020-10-01 00:00:00.000",
+            "sample_format": "csv",
+            "sample_file": "./sample.csv",
+            "tags_file": "",
+            "columns": [{"type": "INT"}, {"type": "DOUBLE", "count":10}, {"type": "BINARY", "len": 16, "count":3}, {"type": "BINARY", "len": 32, "count":6}],
+            "tags": [{"type": "TINYINT", "count":2}, {"type": "BINARY", "len": 16, "count":5}]
+        }]
+    }]
+}