我懒得从头开始编写支持逻辑，所以我正在重用分支上链接答案的函数：

/**
 * Retrieve IDs of posts in branch of menu.
 *
 * @param mixed  $menu
 * @param string $branch_title
 *
 * @link http://wordpress.stackexchange.com/questions/2802/display-a-portion-branch-of-the-menu-tree-using-wp-nav-menu
 *
 * @return array
 */
function get_post_ids_from_menu_branch( $menu, $branch_title ) {

    $menu_object = wp_get_nav_menu_object( $menu );
    $menu_items  = wp_get_nav_menu_items( $menu_object->term_id );
    $items       = submenu_limit( $menu_items, (object) array( \'submenu\' => $branch_title ) );
    $items       = wp_list_filter( $items, array( \'object\' => \'post\' ) );
    $ids         = wp_list_pluck( $items, \'object_id\' );

    return $ids;
}

// example
var_dump( get_post_ids_from_menu_branch( \'Test menu\', \'Level 1\' ) );