一、安装sass-resources-loader

cnpm install sass-resources-loader --save-dev

二、修改build/utils.js

scss: generateLoaders('sass')

变成下面这样：
单个引入：

scss: generateLoaders('sass').concat(
      {
        loader: 'sass-resources-loader',
        options: {
          resources: path.resolve(__dirname, '../src/assets/scss/mixin.scss')
        }
      }
    )

多个引入：

scss: generateLoaders('sass').concat({
            loader: 'sass-resources-loader',
            options: {
                resources: [
                    path.resolve(__dirname, '../src/assets/scss/mixin.scss'),
                    path.resolve(__dirname, '../src/assets/scss/base.scss'),
                ]

            }
        }),

单个使用单独页面引入

往build文件中的webpack.base.conf.js中的module.rules中添加

{
      test: /\.scss$/,
       loaders: ["style", "css", "sass"]
},

然后当前页面引入要用的单个scss

<style lang="scss" scoped>
  @import url('../assets/scss/base.scss');
</style>