Based on the NAM model, which is a lumped hydrological model, the discharge at the Wudaogou Hydrological Station was simulated. Nine flood events with the largest peak flows from the period of 1985 to 2010 were chosen to calibrate the model parameters. Simulation results show that peak flow appeared in advance systematically, and the flood peak phase difference could not be decreased by adjusting model parameters. In order to obtain reasonable results, two improved models are proposed: one is a lumped NAM hydrological model that does not change model parameters but deals with area precipitation by shifting time weighted, and the other is a NAM hydrological model, which is based on sub-catchments and deals with simultaneously weighted area precipitation. Calculation results of the two improved models show that the flood peak phase difference decreases, and the coefficient of determination and the qualified rate increase.