You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query>
    <abusefilters>
      <filter id="1" description="建立沒有wiki語法之頁面" />
      <filter id="2" description="阻止機器人在使用者頁面增加.com連結＆編輯次數小於3次" />
      <filter id="3" description="阻止機器人立即編輯自己的頁面&amp;編輯次數小於兩次" />
      <filter id="4" description="阻止機器人立即編輯自己的對話頁&amp;編輯次數小於兩次" />
      <filter id="5" description="禁止廣告句子" />
    </abusefilters>
  </query>
</api>