Balance of payments surplus, referred to as surplus. Symmetry of balance of payments deficit. In a certain period of time (usually one year), a country's total international income is greater than its total expenditure, which is a surplus. It usually starts with "+".

Surplus means that the total export volume is greater than the total import volume, the difference between foreign exchange inflow and outflow is positive, and foreign exchange reserves are growing positively. After obtaining foreign exchange, export enterprises need to convert foreign exchange into local currency for reproduction, so the demand for local currency increases. From a national perspective, in order to maintain the stability of the exchange rate, it is necessary to issue local currency equal to the increased foreign exchange. Therefore, the demand for the country's currency is greater than the supply.