interbank lending originated from the deposit reserve system of the central bank. When the deposit paid by a commercial bank into the central bank is greater than the deposit balance required by the statutory deposit reserve ratio, the excess reserve of a commercial bank is formed; On the other hand, when the deposits deposited by commercial banks in the central bank are less than the balance required by the statutory deposit reserve ratio, commercial banks should be short in time, otherwise they will be punished by the central bank. When the excess reserves are surplus, commercial banks hope to lend out the surplus funds through the national interbank lending market in order to obtain more income; When the excess reserve is insufficient, commercial banks hope to borrow funds from the market to supplement the shortage of capital positions. Therefore, interbank lending is a short-term credit behavior of financing between commercial banks. This is the first way for commercial banks to consider when the liquidity of funds is difficult, especially temporary difficulties.