<div class="col-lg-3 col-xs-6 paddingLeft com_marginBtm10 choosePlan" v-on:mouseover="changeActive($event)" v-on:mouseout="removeActive($event)">
  流量套餐
</div>

methods:{
   changeActive($event){
       $event.currentTarget.className="col-lg-3 col-xs-6 paddingLeft com_marginBtm10 choosePlan active";
   },
   removeActive($event){
       $event.currentTarget.className="col-lg-3 col-xs-6 paddingLeft com_marginBtm10 choosePlan";
   }
},

    <div class="index_tableTitle clearfix" v-for="(item,index) in table_tit">
     <div class="indexItem">
      <span :title="item.name">{{item.name}}</span>
      <span class="mypor">
       <i class="icon" @mouseenter="enter(index)" @mouseleave="leave()"></i>
       <div v-show="seen&&index==current" class="index-show">
        <div class="tip_Wrapinner">{{item.det}}</div>
       </div>
      </span>
     </div>
    </div>

 export default {
  data(){
   return{
    seen:false,
    current:0
   }
  },
  methods:{
   enter(index){
    this.seen = true;
    this.current = index;
   },
   leave(){
    this.seen = false;
    this.current = null;
   }
  }
 }