A 2D numerical model is established to simulate the flow field and the sediment concentration during construction of Xuwei Harbor surrounding project. The impact of the entrance scale and the layout of the inner harbor on the hydrodynamic characteristics and sediment deposition are studied. The result shows that the hydrodynamic condition near the entrance of the surrounding basin is determined by the ratio of the area in the harbor and the cross section area of the entrance, and the sediment deposition of the waterway and the basin near the entrance is inverse proportional to the hydrodynamic condition. In order to improve the flow condition near the entrance and reduce the siltation intensity in the harbor at the initial stage of the construction of the surrounding basin, the area of the useless waters in the harbor should be reduced and the entrance should be widened appropriately.