Watershed flow concentration is a three dimension hydrological phenomenon, mainly concerning with thelandforms in river network and dynamic characteristics in river channels. Based on the geomorphology andhydrology, this paper gives out a concept model, in which parameters are compulated with the geomorphologicparameters and dynamic characteristic values of river channel. As a nonlinear model with clear concept, it is notonly simple for computation, but also can be used for the computation of watershed flow concentration inungaged basins.