一、效果

 二、代码

<template>
    <el-select class="autoWidth-select" v-model="value" placeholder="请选择">
      <template slot="prefix"> 
        {{(options.find(s => s.value === value) || {}).label}}
      </template>
      <el-option
        v-for="item in options"
        :key="item.value"
        :label="item.label"
        :value="item.value">
      </el-option>
    </el-select>
</template>
<script>
export default {
  data() {
    return {
       options: [{
          value: '选项1',
          label: '炒面炒面炒面'
        }, {
          value: '选项2',
          label: '双皮奶双皮奶双皮奶双皮奶双皮奶双皮奶双皮奶'
        }, {
          value: '选项3',
          label: '蚵仔煎蚵仔煎蚵仔煎'
        }, {
          value: '选项4',
          label: '龙须面'
        }, {
          value: '选项5',
          label: '北京烤鸭'
        }],
        value: '选项1'
    }
  },  
}
</script>
<style scoped >
.autoWidth-select {
  min-width: 120px;
}
.autoWidth-select >>> .el-input__prefix{
    position: relative;
    left: 0px;
    box-sizing: border-box;
    border: 1px solid #ffffff00;
    padding: 0 30px;
    height: 40px;
    line-height: 40px;
    visibility: hidden;
}
.autoWidth-select >>> input{
  position: absolute;
}
</style>