实现效果如下

三级菜单效果图

砰砰砰 ！！！听说不贴代码的博客都是耍流氓(复制即用，请叫我雷锋)

数据源

list: [
        {
          path: "/1",
          name: "导航一",
          icon:'el-icon-menu',
          children: [
            {
              path: "/1/1",
              name: "导航1-1",
              icon:'el-icon-menu',
              children: [
                {
                  path: "/1/1/1",
                  name: "导航1-1-1",
                  icon:'el-icon-menu',
                },
                {
                  path: "/1/1/2",
                  name: "导航1-1-2",
                  icon:'el-icon-menu',
                },
                {
                  path: "/1/1/3",
                  name: "导航1-1-3",
                  icon:'el-icon-menu',
                }
              ]
            },
            {
              path: "/1/2",
              name: "导航1-2",
              icon:'el-icon-menu',
            }
          ]
        },
        {
          path: "/2",
          name: "导航二",
          icon:'el-icon-menu'
        }
      ]

aside.vue

<el-menu
  default-active="1"
  background-color="#545c64"
  text-color="#fff"
  active-text-color="#ffd04b">
  
    <!-- 一级菜单 -->
  <template v-for="item in list">
    <el-submenu v-if="item.children && item.children.length" :index="item.path" :key="item.path">
      <template slot="title"><i :class="item.icon"></i><span>{{item.name}}</span></template>
      
      <!-- 二级菜单 -->
      <template v-for="itemChild in item.children">
        <el-submenu v-if="itemChild.children && itemChild.children.length" :index="itemChild.path" :key="itemChild.path">
            <template slot="title"><i :class="itemChild.icon"></i><span>{{itemChild.name}}</span></template>
            
            <!-- 三级菜单 -->
            <el-menu-item v-for="itemChild_Child in itemChild.children" :index="itemChild_Child .path" :key="itemChild_Child.path">
            <i :class="itemChild_Child.icon"></i><span slot="title">{{itemChild_Child.name}}</span></el-menu-item>
        </el-submenu>
        
        <el-menu-item v-else :index="itemChild.path" :key="itemChild.path"><i :class="itemChild.icon"></i><span slot="title">{{itemChild.name}}</span></el-menu-item>
      </template>
    </el-submenu>
    
    <el-menu-item v-else :index="item.path" :key="item.path"><i :class="item.icon"></i><span slot="title">{{item.name}}</span></el-menu-item>
  </template>

</el-menu>