你想要的是这种效果吧：

找到文件：application\controllers\Topic.php

搜索 ctr+F

$seo_description = $topicone ['title'];

然后用下面的代码替换：

if ($topicone ['price'] != 0 && $haspayprice == 0 && $this->user ['uid'] != $topicone ['authorid']) {
   $seo_description = "付费后可查看文章内容";
  } else {
   $seo_description = cutstr ( trim(clearhtml($topicone ['describtion'])), 140 );
  }