Abstract: Based on the rainstorm and flood process information for the Gudongkou Reservoir Basin, the Xin'anjiang Hydrological model is used to carry out hydrological simulation tests. The simulation results are evaluated with the determinacy coef ficient, the relative error of the flood peak flow and the peak time difference. The parameter sensitivity is analyszed respectively with the deterministic coef fi cient, the relative error and peak time difference of peak flow as the evaluation indexes, and the sensitivity of the model parameters is carried out quantitatively, then the key sensitivity parameters are determined. It provides a reference for the optimization of model structure and the reliability of the model application.