Abstract: A 3D mathematical modeling considering bank erosion is adopted to simulate the fluvial processes of the Shishou bend in the Middle Yangtze River during the early filling of the Three Gorges Reservoir.The locally-adaptive grid system based on non-orthogonal grids is used to calculate the lateral migration in channels due to bank erosion with a composite structure.The observed data of bed deformation from September 2002 to July 2004 is adopted to verify the accuracy of the model,and the calculated results agree well with the measured data.The 3D model can not only simulate the longitudinal bed deformation,but also calculate the lateral migration in alluvial rivers.The fluvial processes in the Shishou bend from July 2004 to December 2016 are forecasted using the 3D model after the filling of the Three Gorges Reservoir,and the calculated results can provide scientific basis for the investigation of river regulation.