1, the base currency has the following five remarkable characteristics: it is the debt of the central bank; Strong liquidity, that is, the holder can use it independently, which is the most active part of all currencies; Derivative, that is, the result of its movement can produce several times the amount of money itself, which has multiple expansion functions.

2. It has a high correlation with all relevant levels of money supply, and its change plays a significant decisive role in the change of money supply.

3. Controllability, that is, the central bank can control it and control the whole money supply by controlling it.