diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index e52f8699100918c3e66ab1e58b4a0b6d7405406a..95104bfb6303826baec2af6bc6f3618bbc5d672a 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -4420,7 +4420,7 @@ static int32_t validateLikeExpr(tSqlExpr* pExpr, STableMeta* pTableMeta, int32_t
 // check for match expression
 static int32_t validateJsonTagExpr(tSqlExpr* pExpr, char* msgBuf) {
   const char* msg1 = "not support json tag column filter";
-  const char* msg2 = "tag json key is too long, exceed to 64";
+  const char* msg2 = "tag json key is invalidate";
   const char* msg3 = "tag json key must be string";
 
   tSqlExpr* pLeft = pExpr->pLeft;
@@ -4430,17 +4430,17 @@ static int32_t validateJsonTagExpr(tSqlExpr* pExpr, char* msgBuf) {
     if (pRight != NULL && !IS_VAR_DATA_TYPE(pRight->value.nType))
       return invalidOperationMsg(msgBuf, msg3);
 
-    if (pRight != NULL && pRight->value.nLen >= TSDB_COL_NAME_LEN)
+    if (pRight != NULL && (pRight->value.nLen > TSDB_MAX_JSON_KEY_LEN || pRight->value.nLen <= 0))
       return invalidOperationMsg(msgBuf, msg2);
   } else {
-    if (pLeft != NULL && pLeft->tokenId == TK_ID && pExpr->tokenId != TK_NULL) {
+    if (pLeft != NULL && pLeft->tokenId == TK_ID && pExpr->tokenId != TK_ISNULL && pExpr->tokenId != TK_NOTNULL) {
       return invalidOperationMsg(msgBuf, msg1);
     }
 
     if (pLeft != NULL && pLeft->tokenId == TK_ARROW) {
       if (pLeft->pRight && !IS_VAR_DATA_TYPE(pLeft->pRight->value.nType))
         return invalidOperationMsg(msgBuf, msg3);
-      if (pLeft->pRight && pLeft->pRight->value.nLen >= TSDB_COL_NAME_LEN)
+      if (pLeft->pRight && (pLeft->pRight->value.nLen > TSDB_MAX_JSON_KEY_LEN || pLeft->pRight->value.nLen <= 0))
         return invalidOperationMsg(msgBuf, msg2);
     }
   }
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index caab7ed809eb9b997b3a01019b70f1e1031e3e55..3ae9a2b2446abbdea1dcb1f33988dc1d5315b26b 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -5210,7 +5210,7 @@ void parseTagValue2Dst(char* result, char* dst){
     char    tagJsonValue[TSDB_MAX_TAGS_LEN] = {0};
     int32_t length = taosUcs4ToMbs(varDataVal(realData),
                                    varDataLen(realData), tagJsonValue);
-    if (length == 0) {
+    if (length < 0) {
       tscError("charset:%s to %s. val:%s convert json value failed.", DEFAULT_UNICODE_ENCODEC, tsCharset,
                (char*)result);
       return;
diff --git a/src/query/src/qFilter.c b/src/query/src/qFilter.c
index 6cb9102cfcb3d1eb05c269b3a5b303a6bda6f1ad..09899fd7eeb3746d82e818758b84dbc95b442694 100644
--- a/src/query/src/qFilter.c
+++ b/src/query/src/qFilter.c
@@ -1161,7 +1161,7 @@ int32_t filterAddGroupUnitFromNode(SFilterInfo *info, tExprNode* tree, SArray *g
   if(pLeft->nodeType == TSQL_NODE_EXPR && pLeft->_node.optr == TSDB_RELATION_ARROW){    // json tag -> operation
     assert(info->pTable != NULL);
     SSchema* schema = pLeft->_node.pLeft->pSchema;
-    if(pLeft->_node.pRight->pVal->nLen >= TSDB_MAX_JSON_KEY_LEN) return TSDB_CODE_TSC_INVALID_COLUMN_LENGTH;
+    if(pLeft->_node.pRight->pVal->nLen > TSDB_MAX_JSON_KEY_LEN) return TSDB_CODE_TSC_INVALID_COLUMN_LENGTH;
     char keyMd5[TSDB_MAX_JSON_KEY_MD5_LEN] = {0};
     jsonKeyMd5(pLeft->_node.pRight->pVal->pz, pLeft->_node.pRight->pVal->nLen, keyMd5);
     memcpy(schema->name, keyMd5, TSDB_MAX_JSON_KEY_MD5_LEN);
@@ -1174,7 +1174,7 @@ int32_t filterAddGroupUnitFromNode(SFilterInfo *info, tExprNode* tree, SArray *g
     pLeft = pLeft->_node.pLeft;   // -> operation use left as input
   }else if(tree->_node.optr == TSDB_RELATION_QUESTION){
     SSchema* schema = pLeft->pSchema;
-    if(tree->_node.pRight->pVal->nLen >= TSDB_MAX_JSON_KEY_LEN) return TSDB_CODE_TSC_INVALID_COLUMN_LENGTH;
+    if(tree->_node.pRight->pVal->nLen > TSDB_MAX_JSON_KEY_LEN) return TSDB_CODE_TSC_INVALID_COLUMN_LENGTH;
     char keyMd5[TSDB_MAX_JSON_KEY_MD5_LEN] = {0};
     jsonKeyMd5(tree->_node.pRight->pVal->pz, tree->_node.pRight->pVal->nLen, keyMd5);
     memcpy(schema->name, keyMd5, TSDB_MAX_JSON_KEY_MD5_LEN);
diff --git a/tests/pytest/stable/json_tag.py b/tests/pytest/stable/json_tag.py
index 619df8dab62f93a5e8b02dd69e40e43dc07a0806..134fdc696078f0343dbac60958481e9cbea74e58 100644
--- a/tests/pytest/stable/json_tag.py
+++ b/tests/pytest/stable/json_tag.py
@@ -61,9 +61,12 @@ class TDTestCase:
         #tdSql.error("select * from db_json_tag_test.jsons1 where jtag->'location'=4")
         tdSql.error("select * from db_json_tag_test.jsons1 where jtag->location='beijing'")
         tdSql.error("select * from db_json_tag_test.jsons1 where jtag->'location'")
+        tdSql.error("select * from db_json_tag_test.jsons1 where jtag->''")
+        tdSql.error("select * from db_json_tag_test.jsons1 where jtag->''=9")
         tdSql.error("select jtag->location from db_json_tag_test.jsons1")
         tdSql.error("select jtag?location from db_json_tag_test.jsons1")
         tdSql.error("select * from db_json_tag_test.jsons1 where jtag?location")
+        tdSql.error("select * from db_json_tag_test.jsons1 where jtag?''")
         tdSql.error("select * from db_json_tag_test.jsons1 where jtag?'location'='beijing'")
 
         # test select condition
@@ -170,12 +173,33 @@ class TDTestCase:
         tdSql.error("CREATE TABLE if not exists db_json_tag_test.jsons1_5 using db_json_tag_test.jsons1 tags('efwewf')")
         tdSql.error("CREATE TABLE if not exists db_json_tag_test.jsons1_5 using db_json_tag_test.jsons1 tags('\t')")
         tdSql.execute("CREATE TABLE if not exists db_json_tag_test.jsons1_6 using db_json_tag_test.jsons1 tags('')")
+        tdSql.query("select jtag from db_json_tag_test.jsons1_6")
+        tdSql.checkData(0, 0, "NULL")
+
         tdSql.execute("CREATE TABLE if not exists db_json_tag_test.jsons1_7 using db_json_tag_test.jsons1 tags('{}')")
+        tdSql.query("select jtag from db_json_tag_test.jsons1_7")
+        tdSql.checkData(0, 0, "NULL")
+
         tdSql.execute("CREATE TABLE if not exists db_json_tag_test.jsons1_8 using db_json_tag_test.jsons1 tags('null')")
+        tdSql.query("select jtag from db_json_tag_test.jsons1_8")
+        tdSql.checkData(0, 0, "NULL")
+
         tdSql.execute("CREATE TABLE if not exists db_json_tag_test.jsons1_9 using db_json_tag_test.jsons1 tags('{\"\":4, \"time\":null}')")
+        tdSql.query("select jtag from db_json_tag_test.jsons1_9")
+        tdSql.checkData(0, 0, "NULL")
+
         tdSql.execute("CREATE TABLE if not exists db_json_tag_test.jsons1_10 using db_json_tag_test.jsons1 tags('{\"k1\":\"\",\"k1\":\"v1\",\"k2\":true,\"k3\":false,\"k4\":55}')")
-        tdSql.query("select * from db_json_tag_test.jsons1 where datastr match 'json and jtag->'location' match 'jin'")
-        tdSql.checkRows(2)
+        tdSql.query("select jtag from db_json_tag_test.jsons1_10")
+        tdSql.checkData(0, 0, "{\"k1\":\"\",\"k2\":true,\"k3\":false,\"k4\":55}")
+
+        tdSql.query("select jtag->'k2' from db_json_tag_test.jsons1_10")
+        tdSql.checkData(0, 0, "true")
+
+        tdSql.query("select jtag from db_json_tag_test.jsons1 where jtag->'k1'=''")
+        tdSql.checkRows(1)
+
+        tdSql.query("select jtag from db_json_tag_test.jsons1 where jtag->'k2'=true")
+        tdSql.checkRows(1)
 
     def stop(self):
         tdSql.close()