Visa and Mastercard are widely accepted throughout China. American Express and other lesser known credit cards are not widely accepted. It is suggested that you contact your credit card company to inform of when and where you will be traveling and that you may be using your credit card abroad.
Refund Insurance
Be aware that though at home you are covered by the refund policy if you purchase goods that are not to your satisfaction, when traveling abroad you should check first with your credit card company before making purchases of expensive goods as you may not be able to obtain a refund if there are no agreements between the credit card issuer and the supplier of the goods. Legal systems change from one country to another and not all of them have this kind of customer protection programs.
Currency Exchange Rate
When traveling overseas, foreign currencies are always an issue. The exchange rate varies between banks and financial institutions, let alone unofficial currency exchangers that wonder in the streets in some countries. With a Credit Card you can always be sure that if you go to an ATM and you retrieve cash, you'll get a secure transaction with an average exchange rate, thus avoiding being ripped off.
Bear in mind though, that in some countries, official exchange rate differs a lot with market's exchange rate and you may want to consider exchanging your currency before traveling or in some other place if you are already in the foreign country. Always consult with trustworthy people, mainly personnel from the hotels and restaurants will let you know how everything works.
Beware of the fees
Credit Card companies usually charge extra fees for oversees transactions. There are other costs implied for them when purchases take place in a foreign country. However, these fees are usually calculated on a percentage basis that shouldn't exceed a 2% of the purchase price. Before traveling consult with your credit card's issuers how much are they charging for overseas purchases. Compare the fees and decide which of your credit cards you should use when you are abroad. This way you will save money and enjoy your vacations knowing you are making the most out of your money.