<el-submenu index="1">
<template slot="title"><i class="el-icon-message"></i>在校班级</template>
<el-menu-item-group v-for="group in onstudyclasses">
<template slot="title">{{group.title}}</template>
<template v-for="c in group.classes">
<el-submenu :index="group.id+'-'+c.id" >
<template slot="title">{{c.title}}</template>
<el-menu-item v-for="student in c.students" :index="c.id+'-'+student.id" @click.native.prevent="clkStudent(student.id)">{{student.name}}</el-menu-item>
</el-submenu>
</template>
</el-menu-item-group>
</el-submenu>
题主您好，请问这个问题解决了吗？我也碰到了相同的问题。