您可以运行一个脚本，该脚本将以编程方式为每篇文章设置特色图像。您可以使用第一个附加图像进行此操作。要获取附加的图像，请对帖子进行查询并循环浏览每个帖子，然后使用get_children() 将post\\u父项设置为循环中的当前post id。

$posts = get_posts( array( \'posts_per_page\' => -1 ));

foreach ( $posts as $post ) {

   $featured = wpse_get_attachments( $post->ID );
   foreach( $featured as $attachment ) {
     $img = set_post_thumbnail( $post->ID, $attachment[\'ID\'] );
   }
   if ( $img )
       echo \'Featured image set for \'. $post->ID; 
}
/**
 * Queries for attached images and returns first.
 *
 * @param int $post_id The post id to check if attachments exist
 * @return array|bool The 1st attached on success false if no attachments
 */
function wpse_get_attachments( $post_id ) {
    return get_children( array(
            \'post_parent\'    => $post_id,
            \'post_type\'      => \'attachment\',
            \'post_mime_type\' => \'image\',
            \'posts_per_page\' => (int)1
        ), ARRAY_A
    );
}

您还可以使用我编写的插件，该插件将通过ajax的管理工具页面实现这一点。http://wordpress.org/extend/plugins/media-tools/