I need information about work visa in china, what is the requirments? im from pakistan.

AIzaz, you should find a job in China first, and then your employer will get you the work permit and an invitation letter of a duly authorized unit.
Next, prepare the relevant documents including your passport and its photocopy, the application form, a passport-style photo, work permit and the invitation letter.
Afterwards, submit the application to the Chinese embassy in Pakistan.