Abstract: In this paper some main risk factors are sifted with in the flood control decision process for the middle reach of the Yangtze River. The risk analysis models are set up for flood control decision considering the following three kinds of information: historical data of rainfall and flood, short-term forecasting of water stage as well as mid-and-long term forecasting of rainfall and flood. In addition, the quantitative descriptions are given for various flood control plans of whether to use the flood diversion areas or flood storage areas in the flood control system of the Yangtze River reach between Three Gorges and Loushan.