Abstract: A watershed drainage network generation model (WDNGM)is developed in the Three Gorges watershed on the basis of the hillslope flow modeling approach and the shortest flow course method for ‘filling sink',using the digital elevation model (DEM).The Xmanjiang model is improvedfor development of a watershed hydrological model characterizing the Three Cxmges watershed.Basedon the hydraulic dynamic theory,a flood routing model of the river channel pattern reservoir in the Three Cxmges,considering the water project operation influences,is established and fully coupled with the watershed hydrologic model.On the GIS platform,a real-time flood forecasting system is developed by integrating the watershed hydrological model,the flood routing model and the WDN GM in the Three Cprges watershed,which its functions are advanced and complete.This system has been installed and test operated by the reservoir control center of Three Gorges Company.