The basic concepts and structure of TOPMODEL are introduced in this paper.As a bridge between the conceptual and the distributed models TOPMODEL has a simple structure clear physical explanation of water movement mechanisms in the watershed and a parsimonious number of parameters.In order to broaden the use of TOPMODEL in simulating watershed runoff in practice the hydrological data of six different watersheds are selected to test TOPMODEL.These six watersheds are located in different regions with different areas and of different climate conditions.For the purposes of comparison the Xinanjiang model is also applied on these watersheds in simulating runoff.It was found that TOPMODEL can succeed in simulating the watershed runoff in nearly every watershed and it is also comparable to the Xinanjiang model in terms of the model efficiency.It is strongly suggested that TOPMODEL be studied and appliedmore extensively in China.