Major credit cards i.e. Visa, Masters, HSBC are accepted throughout Shenzhen. But note that in many establishments only local Chinese and not International Visa etc cards are recognised. Ask first if they accept international cards. JCB and American Express have limited coverage. Cirrus, Plus & Maestro facilities allow owners to withdraw money from banks (but not all bank ATMs. Bank of China ATMs at all Metro stations accept foreign cards). Remember to activate your card for the pin usage. MixC has ATMs for some of the international credit cards, where cash can be withdrawn in those ATMs against your credit limit.
Bank of China, China Merchants Bank, and many but not all Chinese banks accept foreign cards. You may check with your bank to see if they have a local branch here. Most ATMs are open for 24 hours. Some are only opened if you swipe the card at the security doors.
At places in Luo Hu, cash is highly recommended. Some places charge an extra 10% for credit card purchases. The shop assistants will bring you to shops that have credit card processing machines. At shopping centers, remember to check with the cashiers to see if they accept credit cards before making purchases. There are few shopping centers that accept credit card with passport verification, though you may lose your discount on the purchase.
Be careful when getting change from large notes as people may give you Hong Kong dollars instead of Yuan. The Hong Kong dollar is worth less than Yuan.
Click here for a listing of shopping places in Shenzhen