默认情况下，会隐藏一些元框。这些框存储在一个数组中，您可以在中找到wp-admin/includes/template.php#get_hidden_meta_boxes(). 有一个过滤器，因此有机会使用插件：

<?php # -*- coding: utf-8 -*-
/*
Plugin Name: Enable Custom Fields per Default
Version:     1.0
Required:    3.1
Author:      Thomas Scholz
Author URI:  http://toscho.de
License:     GPL
*/
! defined( \'ABSPATH\' ) and exit;
add_filter( \'default_hidden_meta_boxes\', \'enable_custom_fields_per_default\', 20, 1 );

/**
 * Removes custom fields from the default hidden elements.
 *
 * The original ( wp-admin/includes/template.php#get_hidden_meta_boxes() ):
 * array(
 *      \'slugdiv\',
 *      \'trackbacksdiv\',
 *      \'postcustom\',      <-- we need this
 *      \'postexcerpt\',
 *      \'commentstatusdiv\',
 *      \'commentsdiv\',
 *      \'authordiv\',
 *      \'revisionsdiv\'
 * )
 *
 * It has no effect if the user has decided to hide the box.
 * This option is saved in "metaboxhidden_{$screen->id}"
 *
 * @param  array $hidden
 * @return array $hidden
 */
function enable_custom_fields_per_default( $hidden )
{
    foreach ( $hidden as $i => $metabox )
    {
        if ( \'postcustom\' == $metabox )
        {
            unset ( $hidden[$i] );
        }
    }
    return $hidden;
}