You can use your credit cards to withdraw money from banks in China or from ATMs if the symbols and logos of your credit card are shown on the machines. The 5 star hotel desks can exchange Traveler's cheques or foreign currencies to local currency, but you cannot withdraw local currency with your credit card at the hotel desks. Both US dollars and Canadian dollars can be exchanged at those hotels or exchange booths of major airports. You may take a small amount of cash with you and exchange them when necessary.