In recent years,a Y-shaped regulating structure has been applied in the waterway regulation project,which achieved good protecting beach effect.Based on the typical tidal branch channels of Baimao Sandbank segment in the lower Yangtze River,a mathematical model is established to study beach protection with Y-shaped regulating structure.The results show that the beach protection dike is generally placed near the edge of the protected beach,the length of the beach protection dike should cover the stoss side of the beach,and the elevation of the beach protection dike could be equal to the characteristic water level of tidal branching stream.The head submerged dike is generally placed along the ridge line,the length of the head submerged dike could extend to the protected low beach,which can be determined by choosing a stable contour line in the low beach based on years of historical terrain data,and the elevation of the head submerged dike will be able to satisfy the structural safety of buildings.