Third-party depository is the third-party depository of customers' transaction settlement funds, which is a business provided by commercial banks and is often used in securities, futures, real estate and other trading activities. In the past securities trading activities, the trading settlement funds of investors (customers) were uniformly kept by a securities company; After development, the CSRC stipulates that customer transaction settlement funds shall be uniformly deposited by third-party depository institutions, which refer to commercial banks with third-party depository qualifications.