To improve the accuracy of flood forecasting, 13 flood events between 2000 and 2017 were selected from the sections of Lutaizi and Lubeng, and the Xin’anjiang three-source model(XAJ model)was used to simulate the flood events. The Lutaizi basin can be divided into 9 natural sub-basins and the Lubeng basin can be divided into 4 natural sub-basins. Then, the XAJ model was calibrated for these basins. The node generalizability was carried out in the mainstream section of the Huaihe River with flood diversion and flood retarding areas. Combined with the diversion ratio method and the Muskingen method, the simulation method of flood diversion was established, and fairly good forecasting results were obtained. The research results show that: for the relative error of flood volume, the qualified rates of Lutaizi and Lubeng region are both up to 100%, and the Lutaizi reached a qualified rate of 100% in the flood peak, while the Lubeng region reached 92. 3%. In two floods in 2003 and 2007, the relative error and the certainty coefficient of flood peak have been significantly improved.