Through the monetary base and the money- supply multiplier analysis, this article theoretically analyzes the money supply control ability. At the same time the imperfect market economy system of China also makes China more difficult to control the money supply. Moreover under the background of the financial innovation, the relaxes of finance controlling and the whole - world financial market integration, the boundary among money supply quantity of each levels is more difficult to determine, and the expansion coefficient of monetary base has also lost the former stability. This further strengthens the endogenous character of money supply. Through the comprehensive analysis of the complicated factors above, the article discusses the deep reasons why the central bank of China can not control the money supply.