To improve the simulation accuracy in the Chinese semi-humid watershed, this study took the Chenhe Catchment in the semi-humid area as the study area and selected 6 parameters including ZSOILFAC, GWEXP, REFKDT, RETDEPRTFAC, OVROUGHRTFAC and MANNFAC for the sensitivity analysis of WRF-Hydro model parameters. The sensitivity of these parameters was qualitatively analyzed by studying the influence of different parameter value in the reasonable range on the flood simulation and each evaluation index, and the modified Morris screening method was used to quantitatively determine the sensitivity of each parameter. The results show that ZSOILFAC, REFKDT and MANNFAC are very sensitive, and it is suggested to take the value within 0.1 to 1.0, 0.0 to 1.0 and 0.5 to 1.5 respectively.