diff --git a/deps/oblib/src/lib/string/ob_string.h b/deps/oblib/src/lib/string/ob_string.h
index 7121543135c21411c6e901ee90da8a2d4a736599..2a54c4e7cd64a3ca5d65de49020c50b56b9dfb1c 100644
--- a/deps/oblib/src/lib/string/ob_string.h
+++ b/deps/oblib/src/lib/string/ob_string.h
@@ -425,6 +425,23 @@ public:
     return ret;
   }
 
+  const ObString trim_space_only()
+  {
+    ObString ret;
+    if (NULL != ptr_) {
+      char *start = ptr_;
+      char *end = ptr_ + data_length_;
+      while (start < end && ' ' == *start) {
+        start++;
+      }
+      while (start < end && ' ' == *(end - 1)) {
+        end--;
+      }
+      ret.assign_ptr(start, static_cast<obstr_size_t>(end - start));
+    }
+    return ret;
+  }
+
   static ObString make_string(const char* cstr)
   {
     return NULL == cstr ? ObString() : ObString(0, static_cast<obstr_size_t>(strlen(cstr)), const_cast<char*>(cstr));
diff --git a/src/share/system_variable/ob_system_variable.cpp b/src/share/system_variable/ob_system_variable.cpp
index 02c9c5cabd0bb75c9b2a76e11e0034f1ba3d7b20..f88b580dcac4546216332f5bac0fa5f2187241d5 100644
--- a/src/share/system_variable/ob_system_variable.cpp
+++ b/src/share/system_variable/ob_system_variable.cpp
@@ -1457,11 +1457,12 @@ int ObSqlModeVar::do_check_and_convert(ObExecContext& ctx, const ObSetVar& set_v
         ret = OB_ERR_UNEXPECTED;
         LOG_ERROR("unexpected type", K(ret), K(in_val));
       }
+      ObString val_without_space = str_val.trim_space_only();
       if (OB_FAIL(ret)) {
-      } else if (OB_FAIL(find_set(str_val))) {
-        LOG_WARN("fail to find type", K(ret), K(str_val), K(in_val));
-      } else if (OB_FAIL(ob_str_to_sql_mode(str_val, sql_mode))) {
-        LOG_WARN("fail to convert str to sql mode", K(ret), K(str_val), K(in_val));
+      } else if (OB_FAIL(find_set(val_without_space))) {
+        LOG_WARN("fail to find type", K(ret), K(val_without_space), K(in_val));
+      } else if (OB_FAIL(ob_str_to_sql_mode(val_without_space, sql_mode))) {
+        LOG_WARN("fail to convert str to sql mode", K(ret), K(val_without_space), K(in_val));
       }
     } else if (ob_is_int_tc(in_val.get_type())) {
       int64_t int64_val = 0;