I have a credit card for precisely this purpose (it's also general-purpose cash back). It's not as useful as you might expect -- most places in China that accept foreign credit cards do so only through an agreement with a chinese bank that imposes a ridiculously disadvantageous exchange rate. (But there's no "conversion fee" -- the bank generously bills you in USD. How nice of them.) They don't seem to be able to bill your card in yuan directly even though the card supports it.

On the other hand, my debit card from the same bank that also has no foreign currency conversion fee works perfectly to get cash from ATMs.