As long as the credit card is UnionPay, you can swipe your card in Hong Kong, and then it will be automatically converted into the corresponding RMB amount according to the exchange rate for repayment, without manual exchange.

Pay special attention to

In Hong Kong and Macao, local banks generally charge fees, which vary from bank to bank. Please check first.

There are many exchange shops on the streets of Hong Kong and Macao, all of which are privately run. They don't exchange money at the bank exchange rate, and there is no handling fee. The exchange rate varies greatly from store to store. Suggest shopping around. Although there is no handling fee, there is a risk of counterfeit money. Pay attention to prevention and check the quantity when exchanging.