Abstract: Flooding is a high frequency and heavy damage in a natural disaster. So for flood disaster risk assessment, can effectively reduce disaster losses, improve the social and economic benefits. This study used SangZhi, yongding, zhangjiajie area CiLi three sites precipitation data from 1981 to 2010, and the major crops planting area, flood affected area, zhangjiajie inundated area, food and production quantity, and other data, flood risk assessment model is established. According to the daily rainfall data of gamma gamma distribution characteristics, fitting, then analyzed and calculated in zhangjiajie is mainly the eigenvalues of the crop water requirement, for flood risk assessment of major crops. The results show that the high probability of zhangjiajie regional flood risk, relatively low level of flood risk probability is higher; Crop the probability of flooding risk increase gradually from west to east, the greater the water requirement of crops, the lower the probability of flooding risk.