According to the provisions of the financial system, the bookkeeping exchange rate of foreign currency business can be converted by the benchmark exchange rate published by the People's Bank of China on the day of business occurrence or by the benchmark exchange rate published by the People's Bank of China at the beginning of the current business occurrence. In practice, we often encounter such a situation. When overseas personnel bring back a large number of proforma invoices with different dates, accountants will encounter such a choice when reimbursing: whether to use the benchmark exchange rate on the day when the business occurs or the benchmark exchange rate at the beginning of the current period. First of all, the company's financial system should stipulate which exchange rate to adopt. The exchange rate at the beginning of the current period or the day of business occurrence should be selected, and cannot be changed at will after being fixed. It is simple and convenient to choose the exchange rate at the beginning, but after that, the exchange difference may be large. The longer the time interval, the greater the exchange difference, and the accounting information will not be reflected in time and accurately. So I think we should try to choose the exchange rate when the business happens. There are several different understandings of choosing the exchange rate when the business occurs: one is the exchange rate on the invoice day, and the other is the exchange rate on the reimbursement day. So, what exchange rate should we use? In this regard, I think the exchange rate on the day of invoice should be used for businesses with great influence. For small or insignificant businesses, the benchmark exchange rate on the day of reimbursement can be used for simple processing, especially for a large number of small invoices on different dates.