I just downloaded it from http://www.mozilla.org/en-US/mobile
Developer Tools
You can install the mobile version of Firefox to your desktop computer in order to test, provide feedback, and build add-ons.
But I don't know how to install it. I wanna test my web page on Firefox Mobile.
Thank you!
There doesn't appear to be an installer. Just click the download button under developer tools, extract the downloaded zip somewhere, and run fennec.exe from that folder.