The risk assessment index system for flood detention zones is introduced into the projection pursuit model based on the information entropy, and the risk assessment projection values are obtained. According to the results, the use risks of flood detention zones of Huaihe River can be divided into four levels, that is, from high to low: “I level”(projection value≥4. 16), including four flood detention zones and two flood areas of Shouxihu and Baojiwei; “II level”(projection value: 4. 10~4. 16), including four flood areas of Tangyuhu etc. ; “III level”(projection value: 3. 90~4. 16), including seven flood areas of Xiangfuduan etc. ; “IV level”(projection value: 0~3. 90), including four flood areas of Qiujiahu etc.