You need to apply for a work visa to China, the requirements are as following:
1. A valid passport as well as a copy of its information page. Your valid passport must have at least six (6) months of remaining validity and at least one blank visa page in it.
2. Application form: Neatly completed Visa Application Forms (Form V2011A and Form V2011B) with genuine information and signature.
3. Photo: one recently-taken color photo of 2x2 square inch glued or stapled on the application form.
4. "Invitation Letter of Duly Authorized Unit" or "Confirmation Letter of Invitation".
5. The original and a photocopy of the Work Permit for Aliens issued by Ministry of Human Resources and Social Security or the original Foreign Expert's License issued by the Chinese Foreign Expert Bureau.
6. your wife shall provide proof of kinship, e.g. marriage certificate, instead of document for work permit.