I am in China with US passport but need new visa. Can I get three months single entry?

Yes, it is possible, but as I know, single entry is usually issued with 30 days and 3 month validity.

thanks for your reply. i camel as cultural exchange program with" invitation letter" ( swiss company art residency program) i supose to stay until august 26 . i orginally got 6 months single entry from New Yrork and stayed two months in China but i came Hongkong for a week . so hongkong only gave me two weeks chinese visa.
I need to get it in two weeks.
please asvise. if it is possible to three months single entry , how long takes to get it...
Thank you

Have you tried to extend your visa at local PSB? As I know, it is possible to get one if you have invitation letter from a company or individual.