As a national bank, the central bank, on the one hand, exercises the function of international reserve management and acts as an agent for its official foreign exchange reserves, becoming the general supplier and demander of the foreign exchange market; On the other hand, it becomes the supervisor, intervener and manipulator of the foreign exchange market, so as to stabilize the exchange rate, adjust the money supply and realize the monetary policy. In some countries, government authorities act as interveners and manipulators in the foreign exchange market.