效果如下

菜单代码如下

  <el-menu:default-active="menuDefaultActive"class="el-menu-box":text-color="menuTextColor":active-text-color="menuActiveTextColor":unique-opened="true"><!-- 一级菜单 --><template v-for="item in appMenuInfoList"><el-submenuv-if="item.menuList && item.menuList.length":index="item.onlyID":key="item.index"class="second_menu"><template slot="title"><i :class="item.icon" v-if="item.icon" /><span v-if="item.systemName">{{item.systemName}}</span></template><!-- 二级菜单 --><template v-for="itemChild in item.menuList"><el-submenuv-if="itemChild.menuList && itemChild.menuList.length":index="itemChild.onlyID":key="itemChild.index"class="last_menu"><template slot="title"><span>{{ itemChild.sysName || itemChild.systemName }}</span></template><!-- 三级菜单 --><el-menu-itemv-for="itemChild_Child in itemChild.menuList":index="itemChild_Child.onlyID":key="itemChild_Child.index"@click="handleMenuSelect(itemChild_Child)"><span slot="title">{{itemChild_Child.sysName || itemChild_Child.systemName}}</span></el-menu-item></el-submenu><el-menu-itemv-else:index="itemChild.onlyID":key="itemChild.index"@click="handleMenuSelect(itemChild)"><span slot="title">{{ itemChild.sysName || itemChild.systemName }}</span></el-menu-item></template></el-submenu><el-menu-itemv-else:index="item.onlyID":key="item.index"@click="handleMenuSelect(item)"><span slot="title">{{ item.sysName || item.systemName }}</span></el-menu-item></template></el-menu>