The unique topography and location of the strait channels makes the interaction of hydrodynamic and sediment transport，sedimentation，topographic erosion and deposition in or between the channels. Taking the Xiazhi fishing port project as an example，based on the field hydrological survey and the measured topographic data，the dynamic sediment environment and the evolution of seabed erosion and deposition after the implementation of fishing port project are analyzed. The influence to current of the breakwater project of the fishing port is studied through the mathematical model，and the reasons for the changes of seabed erosion and deposition are explained from the dynamic mechanism. From the perspective of dynamic geomorphology，the regulation idea of increasing the width of the gate and restoring the hydrodynamic intensity is put forward. The research can provide a reference for the development of port engineering in similar sea areas.