diff --git a/src/client/src/tscPrepare.c b/src/client/src/tscPrepare.c
index ea6ad8a48d7a9c4b5e992dffe8329735a0f47512..6f8013d2cf8350ca0198bce39a3cb8c4e6e3c230 100644
--- a/src/client/src/tscPrepare.c
+++ b/src/client/src/tscPrepare.c
@@ -1658,7 +1658,7 @@ int taos_stmt_prepare(TAOS_STMT* stmt, const char* sql, unsigned long length) {
   pRes->qId = 0;
   pRes->numOfRows = 0;
 
-  strcpy(pSql->sqlstr, sql);
+  strntolower(pSql->sqlstr, sql, (int32_t)sqlLen);
   tscDebugL("0x%"PRIx64" SQL: %s", pSql->self, pSql->sqlstr);
 
   if (tscIsInsertData(pSql->sqlstr)) {
@@ -1849,6 +1849,7 @@ int taos_stmt_set_tbname_tags(TAOS_STMT* stmt, const char* name, TAOS_BIND* tags
     tscResetSqlCmd(pCmd, false, pSql->self);
     pCmd->insertParam.pTableBlockHashList = hashList;
   }
+  
 
   code = tsParseSql(pStmt->pSql, true);
   if (code == TSDB_CODE_TSC_ACTION_IN_PROGRESS) {
diff --git a/tests/develop-test/1-insert/uppercase_in_stmt.py b/tests/develop-test/1-insert/uppercase_in_stmt.py
new file mode 100644
index 0000000000000000000000000000000000000000..b9372b72cb1f5c30e32dda847bdd2dbe6611fd6b
--- /dev/null
+++ b/tests/develop-test/1-insert/uppercase_in_stmt.py
@@ -0,0 +1,66 @@
+###################################################################
+#           Copyright (c) 2016 by TAOS Technologies, Inc.
+#                     All rights reserved.
+#
+#  This file is proprietary and confidential to TAOS Technologies.
+#  No part of this file may be reproduced, stored, transmitted,
+#  disclosed or used in any form or by any means other than as
+#  expressly provided by the written permission from Jianhui Tao
+#
+###################################################################
+
+# -*- coding: utf-8 -*-
+
+import sys
+from util.log import *
+from util.cases import *
+from util.sql import *
+from util.dnodes import *
+from taos import *
+
+
+class TDTestCase:
+    def caseDescription(self):
+        '''
+        case1<slzhou>: [TD-12977] fix invalid upper case table name of stmt api
+        ''' 
+        return
+    
+    def init(self, conn, logSql):
+        tdLog.debug("start to execute %s" % __file__)
+        tdSql.init(conn.cursor(), logSql)
+        self._conn = conn
+        self._dbname = "TD12977"
+
+    def run(self):
+        tdSql.prepare()
+
+        self._conn.execute("drop database if exists %s" % self._dbname)
+        self._conn.execute("create database if not exists %s" % self._dbname)
+        self._conn.select_db(self._dbname)
+
+        self._conn.execute("create stable STB(ts timestamp, n int) tags(b int)")
+
+        stmt = self._conn.statement("insert into ? using STB tags(?) values(?, ?)")
+        params = new_bind_params(1)
+        params[0].int(4);
+        stmt.set_tbname_tags("ct", params);
+
+        multi_params = new_multi_binds(2);
+        multi_params[0].timestamp([1626861392589, 1626861392590])
+        multi_params[1].int([123,456])
+        stmt.bind_param_batch(multi_params)
+        
+        stmt.execute()
+
+        tdSql.query("select * from stb")
+        tdSql.checkRows(2)
+        stmt.close()
+                
+    
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())
diff --git a/tests/develop-test/fulltest-insert.sh b/tests/develop-test/fulltest-insert.sh
index 532f7e6fc0446f6a68ca0a5e80be070684a71c23..e538abf8e2f9f22e9acbce017a3f42b9a6804818 100755
--- a/tests/develop-test/fulltest-insert.sh
+++ b/tests/develop-test/fulltest-insert.sh
@@ -1 +1,2 @@
-python3 ./test.py -f 1-insert/batchInsert.py
\ No newline at end of file
+python3 ./test.py -f 1-insert/batchInsert.py
+python3 ./test.py -f 1-insert/uppercase_in_stmt.py