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>
    <backlinks>
      <bl pageid="10" ns="0" title="Cheng Hung-Wen Chinese Poem" />
      <bl pageid="45" ns="0" title="Cheng Hung-Wen Video" />
      <bl pageid="49" ns="0" title="Cheng Hung-Wen Biography" />
      <bl pageid="52" ns="0" title="Cheng Hung-Wen News" />
      <bl pageid="118" ns="0" title="Cheng Hung-Wen Videos" />
      <bl pageid="119" ns="0" title="Cheng Hung-Wen big events" />
      <bl pageid="285" ns="0" title="Q-version:Hung Wen" />
      <bl pageid="287" ns="10" title="Template:Cheng Hung-Wen Q-version" />
      <bl pageid="542" ns="0" title="Cheng Hung-Wen。The spiritual power of poem" />
    </backlinks>
  </query>
</api>