diff --git a/tools/shell/src/shellEngine.c b/tools/shell/src/shellEngine.c
index e216d597a3ed3486ba88d84835bbd4fdee2ed6bb..d5c765e8c5b0fcf38080a58e605a52e29a859bb2 100644
--- a/tools/shell/src/shellEngine.c
+++ b/tools/shell/src/shellEngine.c
@@ -282,6 +282,7 @@ char *shellFormatTimestamp(char *buf, int64_t val, int32_t precision) {
 
 void shellDumpFieldToFile(TdFilePtr pFile, const char *val, TAOS_FIELD *field, int32_t length, int32_t precision) {
   if (val == NULL) {
+    taosFprintfFile(pFile, "NULL");
     return;
   }