going from united states to chengdu on sept 4 2013 how many luggages and how big can i bring

Which airline company do you use?
As far as I know, different airline companies have different rules for the luggages. Generally speaking, you can take 2 pieces of checked in luggage with one no larger than 32kg. The handbag is not bigger than 8 to 9kg.
In my opinion, you need to contact the airline company to confirm the luggage problem to make sure.