在functions.php里面添加功能函数：

function dm_the_thumbnail() { global $post; if ( has_post_thumbnail() ) { echo '<div class="pic"><a href="'.get_permalink().'">'; $domsxe = simplexml_load_string(get_the_post_thumbnail()); $thumbnailsrc = $domsxe->attributes()->src; echo '<img src="'.$thumbnailsrc.'" alt="'.trim(strip_tags( $post->post_title )).'" />'; echo '</a></div>'; } else {$content = $post->post_content; preg_match_all('/<img.*?(?: |\\t|\\r|\\n)?src=[\'"]?(.+?)[\'"]?(?:(?: |\\t|\\r|\\n)+.*?)?>/sim', $content, $strResult, PREG_PATTERN_ORDER); $n = count($strResult[1]); $random = mt_rand(1, 40); if($n > 0){ echo '<div class="pic"><a href="'.get_permalink().'"><img src="'.$strResult[1][0].'" alt="'.get_the_title().'" title="'.get_the_title().'"/></a></div>'; }else {echo '<div class="pic"><a href="'.get_permalink().'"><img src="'.get_bloginfo('template_url').'/images/random/'.$random.'.jpg" alt="'.get_the_title().'" title="'.get_the_title().'"/></a></div>'; } } } add_theme_support('post-thumbnails'); set_post_thumbnail_size(100, 140, true);

然后在首页输出文章摘要的地方调用：<?php dm_the_thumbnail();?>

当文章没有图片的时候随机获取主题目录下的/images/random/目录里面的图片，所一要在你的主题目录下创建这个目录文件夹images/random/，然后在random文件夹内放置40张jpg图片，命名方式为1~40。红色部分自定义修改。