The existing Yushan Islands reclamation has caused the hydrodynamic change and reformed the surrounding seabed. By comparison of the bathymetry before and after the construction，and referring to the numerical model results，we know that the south and north deep water channels of the islands area further grow，and siltation occurrs in part of the nearshore area. The bathymetric evolution leads to a positive influence on the port water depth maintenance in the deepwater area，improves the water depth condition in front of the coastline，and contributes to the future construction of large quay berths. However，it increases the difficulty of the water depth maintenance in the nearshore berth area and the further reclamation on the west area at the same time.