diff --git a/include/neu_data_expr.h b/include/neu_data_expr.h
index d574908b..1b3237fe 100644
--- a/include/neu_data_expr.h
+++ b/include/neu_data_expr.h
@@ -182,6 +182,7 @@ static inline neu_dtype_e neu_flags_type_in_dtype(neu_dtype_e type)
 }
 
 neu_dtype_e neu_dvalue_get_type(neu_data_val_t *val);
+neu_dtype_e neu_dvalue_get_value_type(neu_data_val_t *val);
 
 /*
  * declare all basic function for neu_data_val_t
diff --git a/src/base/neu_data_expr.c b/src/base/neu_data_expr.c
index 153522b8..d8a0479b 100644
--- a/src/base/neu_data_expr.c
+++ b/src/base/neu_data_expr.c
@@ -161,6 +161,11 @@ neu_dtype_e neu_dvalue_get_type(neu_data_val_t *val)
     return val->type;
 }
 
+neu_dtype_e neu_dvalue_get_value_type(neu_data_val_t *val)
+{
+    return val->type & (NEU_DTYPE_FLAGS_START - 1);
+}
+
 /* new a normal neu_data_val_t with external buffer */
 neu_data_val_t *neu_dvalue_new(neu_dtype_e type)
 {