TOPKAPI is a physically based distributed hydrologic model.This paper makes further development of the TOPKAPI model by introducing new components including interception,infiltration,percolation and groundwater flow,and modifying the sub-surface flow component,aiming at developing a comprehensive,fully-distributed TOPKAPI model.A first try is carried out in this study to derive information from public domain through internet on the topo-graphy,soil and vegetation types for a case study Chinese catchment -- - Upper Xixian catchment in Huaihe River with an area of about10,000km 2 ,and to apply the new TOPKAPI model to the test catchment for flood simulation.The simulation results are satisfactory.