Abstract: This paper describes the theretical background of the TOPMODEL and the variable-source-area concept of stre am flow generation as well as the characteristics of TOPMODEL simulating hydrological response using different spatial distributions of the topographic index.All of the TOPMODEL's applications be fore are only limited on hillslope scale,the paper tries to widen the range of its applications and tests its applied result in ordinary catchment.Huaihe basin is chosed as the study area,and the TOPMODEL is made preliminary comparison with the Xinanjiang model.