Do you mean that you want the Firefox user interface (menu bar and other toolbars) in the Chinese language? If the Firefox user interface (menu bar) is in the wrong language or if you want to change the current language then you can get Firefox in the language of your choice here: * Firefox 5.0.x: http://www.mozilla.com/en-US/firefox/all.html * Uninstall the current Firefox version, but make sure that you do not remove your personal data. * Install the new Firefox version of the wanted language.