HK airport can make the money exchange.
Unless can exchange in Mainland China, A typical Chinese service center, usually have long queues of people so you might have to wait on line for a long time in order to change your foreign currency into RMB. Besides, not every bank in China offers currency exchange service. Pls. check:
http://www.ecomeego.com/Accommodation/article/Banking.htmlGenerally, you should be able to make cash advance from ATM machines, with service charge if you have international credit card or debit card. You can find ATM machines everywhere.