Abstract: A digital elevation model(DEM)-based distributed model is proposed to simulate the saturation-excess mechanism of runoff generation. With the establishment of the relationship between the soil water storage capacity and the topographical index,the spatial distribution of the soil water storage capacity over the watershed is simulated in the model. The direction of the overland flow is determined by using the multiple-direction allocation method rather than the steepest slope method. The results show that the model is capable of simulating the observed hydrographs at nearly the same efficiency as those of the Xinanjiang model and TOPMODEL,and the simulated spatial distribution of the soil moisture content over the whole watershed is reasonably in accordance with the hydrological reality.