On the basis of the hydrological characteristics of Baiyun Mountain basin water reservoir of Futian，Xin’anjiang hydrologic model of three water sources was used to simulate the daily runoff process，by setting the model parameters，the optimal adjustment of the annual runoff error as the objective function，and obtain relatively optimal results.The flood forecasting model for Baiyun Mountain reservoir was established，daily model simulation results for Baiyun Mountain reservoir basin show that the percent of pass of annual runoff depth was 100% for the calibration data of 9 years and validation data of 7 years.The results show that Xin’An River(three water source)model can be used in Baiyun Mountain reservoir，the forecasting model has good effect，high precision and reasonable and it can be taken as reference.