diff --git a/components/grid/col.tsx b/components/grid/col.tsx
index 4205b48007..f611d98499 100644
--- a/components/grid/col.tsx
+++ b/components/grid/col.tsx
@@ -3,11 +3,12 @@ import * as React from 'react';
 import { ConfigContext } from '../config-provider';
 import RowContext from './RowContext';
 import { useColStyle } from './style';
+import type { LiteralUnion } from '../_util/type';
 
 // https://github.com/ant-design/ant-design/issues/14324
 type ColSpanType = number | string;
 
-type FlexType = number | 'none' | 'auto' | string;
+type FlexType = number | LiteralUnion<'none' | 'auto'>;
 
 export interface ColSize {
   flex?: FlexType;