element 嵌套路由跳轉(zhuǎn)子路由？

為什么點(diǎn)擊2-1選項(xiàng)的時(shí)候走的路由["dataCalculation", "one"]，網(wǎng)址顯示http://localhost:8080/#/one 
顯示的頁(yè)面卻是這個(gè)父路由dataCalculation的組件

menu導(dǎo)航

<el-menu :default-active="$router.path" class="el-menu-demo" mode="horizontal" router>
        <el-menu-item index="/" icon="el-icon-search">1</el-menu-item>
        <el-submenu index="dataCalculation">
            <template slot="title">2</template>
            <el-menu-item index="one">2-1</el-menu-item>
        </el-submenu>
    </el-menu>
    
    <router-view></router-view>

路由

 routes: [
    {
      path: '/',
      name: 'HelloWorld',
      component: HelloWorld
    },
    {
      path: '/dataCalculation',
      component: DataCalculation,
      children: [
        { path: '/one', component: DataCalculationOne}
      ]
    }
  ]