postcss-px2rem插件配置不当引起的；
在vue-loader.config.js增加了两个配置

'use strict'
const utils = require('./utils')
const config = require('../config')
const isProduction = process.env.NODE_ENV === 'production'
const sourceMapEnabled = isProduction
  ? config.build.productionSourceMap
  : config.dev.cssSourceMap

module.exports = {
  loaders: utils.cssLoaders({
    sourceMap: sourceMapEnabled,
    extract: isProduction,
    usePostCSS: true//这里设置为true,否则vue引入css会报错
  }),
  postcss: [//postcss配置
    require('postcss-px2rem')({remUnit: 37.5}),
  ],
  cssSourceMap: sourceMapEnabled,
  cacheBusting: config.dev.cacheBusting,
  transformToRequire: {
    video: ['src', 'poster'],
    source: 'src',
    img: 'src',
    image: 'xlink:href'
  }
}