There are two ways to charge UnionPay according to the exchange rate of Hong Kong dollars and RMB. 1. Charge in local currency. 2.(dcc transaction) The so-called dcc is dynamic currency conversion. If the cashier uses dcc, the currency with low card issuance when you swipe your card is RMB, but the owner can't use RMB, so RMB has to be converted into US dollars. So the bill will show that the dollar dcc transaction is very bad, which will make cardholders pay more, but DCC is good for merchants. If the fee charged by the merchant is small, you can search DCC.