SOURCE

var Main = {
   methods:{
    	 showRowDetail(row, expandedRows) {
       		setTimeout(() => {
    		     this.width = "99.99%"
    		  },10)
        	setTimeout(() => {
    		     this.width = "100%"
    		  },50)
       }
    },
    data() {
      return {
        width:'100%',
        tableData5: [{
          id: '12987122',
          name: '好滋好味鸡蛋仔',
          category: '江浙小吃、小吃零食',
          desc: '荷兰优质淡奶，奶香浓而不腻',
          address: '上海市普陀区真北路',
          shop: '王小虎夫妻店',
          shopId: '10333'
        }, {
          id: '12987123',
          name: '好滋好味鸡蛋仔',
          category: '江浙小吃、小吃零食',
          desc: '荷兰优质淡奶，奶香浓而不腻',
          address: '上海市普陀区真北路',
          shop: '王小虎夫妻店',
          shopId: '10333'
        }, {
          id: '12987125',
          name: '好滋好味鸡蛋仔',
          category: '江浙小吃、小吃零食',
          desc: '荷兰优质淡奶，奶香浓而不腻',
          address: '上海市普陀区真北路',
          shop: '王小虎夫妻店',
          shopId: '10333'
        }, {
          id: '12987126',
          name: '好滋好味鸡蛋仔',
          category: '江浙小吃、小吃零食',
          desc: '荷兰优质淡奶，奶香浓而不腻',
          address: '上海市普陀区真北路',
          shop: '王小虎夫妻店',
          shopId: '10333'
        }]
      }
    }
  }
var Ctor = Vue.extend(Main)
new Ctor().$mount('#app')

<script src="//unpkg.com/vue/dist/vue.js"></script>
<script src="//unpkg.com/element-ui@2.6.0/lib/index.js"></script>
<div id="app">
<template>
<div >
  <el-table :style="{width:width}"
  border
    :data="tableData5"
    style="width: 100%" height="250" @expand-change="showRowDetail">
    <el-table-column type="expand"  >
      <template slot-scope="props">
        <el-form label-position="left" inline class="demo-table-expand">
          <el-form-item label="商品名称">
            <span>{{ props.row.name }}</span>
          </el-form-item>
          <el-form-item label="所属店铺">
            <span>{{ props.row.shop }}</span>
          </el-form-item>
          <el-form-item label="商品 ID">
            <span>{{ props.row.id }}</span>
          </el-form-item>
          <el-form-item label="店铺 ID">
            <span>{{ props.row.shopId }}</span>
          </el-form-item>
          <el-form-item label="商品分类">
            <span>{{ props.row.category }}</span>
          </el-form-item>
          <el-form-item label="店铺地址">
            <span>{{ props.row.address }}</span>
          </el-form-item>
          <el-form-item label="商品描述">
            <span>{{ props.row.desc }}</span>
          </el-form-item>
        </el-form>
      </template>
    </el-table-column>
    <el-table-column
      label="商品 ID"
      prop="id">
    </el-table-column>
    <el-table-column
      label="商品名称"
      prop="name">
    </el-table-column>
    <el-table-column
      label="描述"
      prop="desc">
    </el-table-column>
  </el-table>
  </div>
</template>
</div>

@import url("//unpkg.com/element-ui@2.6.0/lib/theme-chalk/index.css");
.demo-table-expand {
  font-size: 0;
}

.demo-table-expand label {
  width: 90px;
  color: #99a9bf;
}

.demo-table-expand .el-form-item {
  margin-right: 0;
  margin-bottom: 0;
  width: 50%;
}