我为此编写了一个插件，但从未发布过：

用法：

在下拉列表中，您有一个所有自定义字段的列表，因此只需选择要筛选的字段，然后单击“筛选”。如果要筛选到自定义字段的特定值，请选择该字段的名称，输入所需的值，然后单击“筛选”。

<?php
/*
Plugin Name: Admin Filter BY Custom Fields
Plugin URI: http://en.bainternet.info
Description: Filter posts or pages in admin by custom fields (post meta)
Version: 1.0
Author: Bainternet
Author URI: http://en.bainternet.info
*/



add_filter( \'parse_query\', \'ba_admin_posts_filter\' );
add_action( \'restrict_manage_posts\', \'ba_admin_posts_filter_restrict_manage_posts\' );

function ba_admin_posts_filter( $query )
{
    global $pagenow;
    if ( is_admin() && $pagenow==\'edit.php\' && isset($_GET[\'ADMIN_FILTER_FIELD_NAME\']) && $_GET[\'ADMIN_FILTER_FIELD_NAME\'] != \'\') {
        $query->query_vars[\'meta_key\'] = $_GET[\'ADMIN_FILTER_FIELD_NAME\'];
    if (isset($_GET[\'ADMIN_FILTER_FIELD_VALUE\']) && $_GET[\'ADMIN_FILTER_FIELD_VALUE\'] != \'\')
        $query->query_vars[\'meta_value\'] = $_GET[\'ADMIN_FILTER_FIELD_VALUE\'];
    }
}

function ba_admin_posts_filter_restrict_manage_posts()
{
    global $wpdb;
    $sql = \'SELECT DISTINCT meta_key FROM \'.$wpdb->postmeta.\' ORDER BY 1\';
    $fields = $wpdb->get_results($sql, ARRAY_N);
?>
<select name="ADMIN_FILTER_FIELD_NAME">
<option value=""><?php _e(\'Filter By Custom Fields\', \'baapf\'); ?></option>
<?php
    $current = isset($_GET[\'ADMIN_FILTER_FIELD_NAME\'])? $_GET[\'ADMIN_FILTER_FIELD_NAME\']:\'\';
    $current_v = isset($_GET[\'ADMIN_FILTER_FIELD_VALUE\'])? $_GET[\'ADMIN_FILTER_FIELD_VALUE\']:\'\';
    foreach ($fields as $field) {
        if (substr($field[0],0,1) != "_"){
        printf
            (
                \'<option value="%s"%s>%s</option>\',
                $field[0],
                $field[0] == $current? \' selected="selected"\':\'\',
                $field[0]
            );
        }
    }
?>
</select> <?php _e(\'Value:\', \'baapf\'); ?><input type="TEXT" name="ADMIN_FILTER_FIELD_VALUE" value="<?php echo $current_v; ?>" />
<?php
}