Abstract: On the basis of the concept of riverregime and Hermite's triple interpolatingfunction,a generating method of 2D riverregimefitted orthgonal quadrilateral grid for river channels is proposed.Combining with simplified depthaveragegoverning equations of fluid mechanics under boundary layer coordinates and SIMPLER algorithm,a 2D mathematical model for river channels is developed.As an engineering illustration of application,the research of grid generation and watersediment simulation for the river reaches from the Gezhouba Project to MopanxiGauge Station is conducted.Primary features of this gridgenerating method arediscussed.