Beginning November 2014, 10 year multiple entry visas became the standard issue for US passport holders (with at least a year validity remaining in their passports) applying for a China visa. This does not apply for visits to a conference, trade show or exhibition. Also, for employees of a Government entity or who are visiting a Government entity
As long as you have not had any major changes with your new passport (name change, gender change, etc), your China visa will remain valid in your expired passport as long as you travel with both your old and new passports together. Please note that China visas cannot be transferred to a new passport.
Don't want to carry both passports? You are able to apply for a new China visa and provide the previous passport so the current visa can be canceled. If you cannot provide the current visa, you must request via a letter to the consulate that your current China visa be canceled, and a new visa issued in the new passport. This is at the consulate's discretion, and we cannot guarantee that the new visa will be issued.