diff --git a/source/libs/parser/src/parUtil.c b/source/libs/parser/src/parUtil.c
index 85c84af05b9d0304f4967d7cbe381e1721663eb8..652ed10ce8b71c71c8eaa640dde145499fe69098 100644
--- a/source/libs/parser/src/parUtil.c
+++ b/source/libs/parser/src/parUtil.c
@@ -330,7 +330,7 @@ int parseJsontoTagData(const char* json, SKVRowBuilder* kvRowBuilder, SMsgBuf* p
   // set json NULL data
   uint8_t jsonNULL = TSDB_DATA_TYPE_NULL;
   int     jsonIndex = startColId + 1;
-  if (!json || strcasecmp(json, TSDB_DATA_NULL_STR_L) == 0) {
+  if (!json || strtrim((char*)json) == 0 ||strcasecmp(json, TSDB_DATA_NULL_STR_L) == 0) {
     tdAddColToKVRow(kvRowBuilder, jsonIndex, &jsonNULL, CHAR_BYTES);
     return TSDB_CODE_SUCCESS;
   }
diff --git a/source/util/src/tutil.c b/source/util/src/tutil.c
index adb6a37ba737fbf1ccafe35231853f8a2fc4cfc8..0534eb3462f92a6ae4252efed389b0d309412c01 100644
--- a/source/util/src/tutil.c
+++ b/source/util/src/tutil.c
@@ -52,7 +52,7 @@ size_t strtrim(char *z) {
   int32_t j = 0;
 
   int32_t delta = 0;
-  while (z[j] == ' ') {
+  while (isspace(z[j])) {
     ++j;
   }
 
@@ -65,9 +65,9 @@ size_t strtrim(char *z) {
 
   int32_t stop = 0;
   while (z[j] != 0) {
-    if (z[j] == ' ' && stop == 0) {
+    if (isspace(z[j]) && stop == 0) {
       stop = j;
-    } else if (z[j] != ' ' && stop != 0) {
+    } else if (!isspace(z[j]) && stop != 0) {
       stop = 0;
     }