The land cover and landform in a watershed is in fact a mosaic, in order to quantify the hydrological responses of complex regions to storm events, a distributed model has been developed for the purpose. The model utilizes a distributed approach by dividing the entire simulation domain into regular cells. It has the capacity to simulate the hydrograph of each cell, namely the space-time distributions in a watershed. And Geographic Information Systems (GIS) technologies can be used effectively to visualize, analyze and model the large-scale spatial data. The model has been utilized in the Heicaohe watershed in Zhenba county, Shaanxi province and the simulated result agrees well with the measured data.