The following documents are required at the time of the visa application at a U.S. consulate abroad.
Original I-797, Notice of Action.
Copy of the petition and supporting documents as filed with the USCIS. (From my experience, not necessary).
Form DS-156, Nonimmigrant Visa Application. This form requires that one color passport-size photograph of the applicant be attached to it. The form will be provided at the consulate for completion by the applicant. You may also view or download this form by going to: http://travel.state.gov/DS-0156.pdf.
Form DS-157 for males between the ages of 16 and 45. The form will be provided at the consulate for completion by the applicant. You may also view or download this form by going to http://travel.state.gov/new157.html.
Passport. The Passport must have one entire blank page and valid for at least six months beyond the date of the visa request.
A visa processing fee of US~$100 as well as any other reciprocity fees charged by the consulate.
Employment Verification Letter with two-to-three recent paystubs.
Make an appointent at consulate via phone. US consulate charges your phone appointment, you need to buy calling mintues online from them before you can be put througth. (check US consulate China web for detail procedures).
The visa is valid with 2 entries within first 3 months for chinese H1-B holder.
I did 3 times for last 4 years without any problem at all.