In order to investigate the influence of different model structures on runoff simulation in semi-arid and semi-humid basins with complex runoff generation mechanisms,the CASC2D model and GSSHA model were used to simulate eight flood events from 1964 to 2000 in the Luanchuan Basin using the same digital elevation model (DEM) data,land cover data,and soil data. The CASC2D model is based on the excess-infiltration mechanism,and the GSSHA model is based on the CASC2D model through addition of groundwater runoff and transformation of the Green-Ampt equation into the Richards equation to calculate the infiltration. The runoff simulation results show that the GSSHA model performs well in the Luanchuan Basin. Compared with the CASC2D model,the simulation of flood peak,runoff depth,and the deterministic coefficient are highly improved by the GSSHA model except for peak time error.