Yangshan deepwater port was formed by blocking up the branched channels and connecting the inlets. The change in boundary conditions influenced the flow structure and sediment movement, which in turn affected the topographic evolution. Applying the“ measuring suspended sediment concentration based on the ADCP backscatter”technology, this article presents the overall character of the suspended sediment movement. Analysis results show that the sediment concentration distribution of Yangshan port has a slight difference between the flood and ebb. The sediment carrying capacity of flood in the main channel is greater than that of the ebb.However, it has a contrary character in the north and south inlets. Huge sediment runoff goes through the Yangshan port. The underwater topography scours slightly in the spring tide, and keeps the balance between erosion and deposition in the moderate tide, and deposits in the neap tide. In relative terms, the power of the flood plays a leading role in the underwater topographic evolution of the Yangshan port. In other words, the sediment carried by the flood from the eastern will deposit in the southwest area of the port, and the neap tide contributes the main effect. Meanwhile, the three inlets of the north and south island chain play an important role in separating sediment from the main channel, and reducing the deposition.