Language depends on what version of license you've bought. If you've bought a 'Chinese' license, you're stuck with 'Mandarin' or 'Cantonese' UI language.
If you purchased a Multi-lingual license (which I doubt they sell these days) and if you did install the 'optional language packs' when installing Photoshop, go to Photoshop Preferences (Edit > Preferences in Windows, Photoshop > Preferences in Mac) > Interface > UI Language - change here.
Also, keep in mind that if you do change the language with multi-language installation or change your locale, Photoshop may ask you to re-enter and re-activate your license.
Oh, I purchased a "Chinese" license. It's mean i have to purchase a "English" license again, or any language package can be used in this case?
thanks a lot.
Sorry, but yes, you should purchase the English license again.