At present, the deposit reserve ratio of our large commercial banks is 15%, and that of small and medium-sized banks is 12%, that is to say, depositors' deposits are 100 yuan, and large commercial banks should pay 15 yuan to the central bank to prevent liquidity payment risks and ensure bank credit payment. Suppose a foreign trade enterprise recycles export products of100000 USD, but China has a compulsory foreign exchange settlement system. In other words, when foreign customers remit $6,543,800,000+,the enterprise obtains $65,000,000 from domestic banks. Generally, foreign exchange transactions are basically conducted in big commercial banks such as Bank of China, and Bank of China will hand over 15% of 65 million foreign exchange to the central bank. If the deposit reserve is raised, the central bank will charge it.