There are several channels for foreign exchange to flow into China: one is foreign trade export income, part of which is sold to commercial banks, and the other part becomes foreign exchange deposits of enterprises (some enterprises can keep 15% of foreign exchange income). Second, overseas remittances, mainly labor income and various overseas transfer payments, mainly form residents' foreign exchange savings deposits. Third, foreign investment is mainly in the form of corporate demand deposits. Fourth, all kinds of institutional legal persons raise funds in the form of loans, issuing stocks or bonds abroad, and this part of foreign exchange is finally manifested as corporate deposits. There are four main channels for foreign exchange outflow: first, foreign trade enterprises import goods. Second, personal use of foreign exchange is mainly used for transfer payments such as traveling abroad and studying abroad. The third is the overseas investment of enterprises. The fourth is the remittance of profits of foreign-funded enterprises.