1.npm i vant -S

2 按需引入
安装babel-plugin-import

npm i babel-plugin-import -D

3 需要在main.js引入

import 'vant/lib/index.css';

4 需要在根目录新建一个babel.config.js

module.exports = {
  presets: ['@vue/cli-plugin-babel/preset'],
  plugins: [
    
    ["import", {
      "libraryName": "vant",
      "libraryDirectory": "es",
      "style": true
    }]
  ]
}