diff --git a/source/libs/function/src/builtins.c b/source/libs/function/src/builtins.c
index 7e9fc7d80ef4cdb2c0660dbad15b7e04af9aab21..c04f8888c8072182f629b0ace3151adc99a6a1aa 100644
--- a/source/libs/function/src/builtins.c
+++ b/source/libs/function/src/builtins.c
@@ -409,7 +409,7 @@ static int32_t translateToJson(SFunctionNode* pFunc, char* pErrBuf, int32_t len)
     return invaildFuncParaTypeErrMsg(pErrBuf, len, pFunc->functionName);
   }
 
-  pFunc->node.resType = (SDataType) { .bytes = tDataTypes[TSDB_DATA_TYPE_JSON].bytes, .type = TSDB_DATA_TYPE_JSON};
+  pFunc->node.resType = (SDataType) { .bytes = tDataTypes[TSDB_DATA_TYPE_BINARY].bytes, .type = TSDB_DATA_TYPE_BINARY};
   return TSDB_CODE_SUCCESS;
 }
 
diff --git a/source/libs/scalar/src/sclfunc.c b/source/libs/scalar/src/sclfunc.c
index 8681c1dd473fdf411e00b0f2b776faf376aa996f..16a4d768ba1b3a469c725851ab22af0fc0108487 100644
--- a/source/libs/scalar/src/sclfunc.c
+++ b/source/libs/scalar/src/sclfunc.c
@@ -887,13 +887,13 @@ int32_t toJsonFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOu
     return TSDB_CODE_FAILED;
   }
 
-  char *input = pInput[0].columnData->pData + pInput[0].columnData->varmeta.offset[0];
-  char *tmp = taosMemoryCalloc(pInput[0].columnData->info.bytes + 1, 1);
+  char tmp[TSDB_MAX_JSON_TAG_LEN] = {0};
   for (int32_t i = 0; i < pInput[0].numOfRows; ++i) {
     if (colDataIsNull_s(pInput[0].columnData, i)) {
       colDataAppendNULL(pOutput->columnData, i);
       continue;
     }
+    char *input = pInput[0].columnData->pData + pInput[0].columnData->varmeta.offset[i];
 
     if(type == TSDB_DATA_TYPE_NCHAR){
       if (varDataTLen(input) > TSDB_MAX_JSON_TAG_LEN){
@@ -912,7 +912,7 @@ int32_t toJsonFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOu
         continue;
       }
       memcpy(tmp, varDataVal(input), varDataLen(input));
-      tmp[varDataTLen(input)] = 0;
+      tmp[varDataLen(input)] = 0;
     }
 
     if(!tjsonValidateJson(tmp)){
@@ -921,9 +921,7 @@ int32_t toJsonFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOu
     }
 
     colDataAppend(pOutput->columnData, i, input, false);
-    input += varDataTLen(input);
   }
-  taosMemoryFree(tmp);
 
   pOutput->numOfRows = pInput->numOfRows;
 
diff --git a/source/util/src/tjson.c b/source/util/src/tjson.c
index 59dab76989bacd88e6b56781a08399894d949b88..0b9727e0bf666b660000d4a0a57b72a6eff65fcd 100644
--- a/source/util/src/tjson.c
+++ b/source/util/src/tjson.c
@@ -300,8 +300,8 @@ bool tjsonValidateJson(const char *jIn) {
 
     char* jsonKey = item->string;
     if (!jsonKey) return false;
-    for (size_t j = 0; j < strlen(jsonKey); ++i) {
-      if (isprint(jsonKey[i]) == 0) return false;
+    for (size_t j = 0; j < strlen(jsonKey); ++j) {
+      if (isprint(jsonKey[j]) == 0) return false;
     }
 
     if (item->type == cJSON_Object || item->type == cJSON_Array) {