1、下载lib-flexible

npm i lib-flexible --save

2、在main.js中引入lib-flexible

import 'lib-flexible/flexible'

3、安装postcss-px2rem

npm i postcss-px2rem --save

4、安装px2rem-loader

npm i px2rem-loader --save

5、配置px2rem-loader

在build/utils.js找到generateLoaders方法，添加以下配置：

const px2remLoader = {
    loader: 'px2rem-loader',
    options: {
      remUnit: 37.5
    }
  }


  // generate loader string to be used with extract text plugin
  function generateLoaders (loader, loaderOptions) {
    var loaders = [cssLoader,px2remLoader]
    if (loader) {
      loaders.push({
        loader: loader + '-loader',
        options: Object.assign({}, loaderOptions, {
          sourceMap: options.sourceMap
        })
      })
    }

    // Extract CSS when that option is specified
    // (which is the case during production build)
    if (options.extract) {
      return ExtractTextPlugin.extract({
        use: loaders,
        publicPath:'../../',
        fallback: 'vue-style-loader'
      })
    } else {
      return ['vue-style-loader'].concat(loaders)
    }
  }

设置完成后重启项目，打开浏览器，可以看到px已经被转化成rem