This paper studies the mathematical model of tidal currents and analyze sediment siltation for the planar layout design requirement of the LNG wharf project on Zhiwan Island. On the basis of the hydrodynamic simulations and the empirical equation of siltation at the wharf，the intensity of sediment siltation under normal and extreme weather at the wharf and berths is calculated before and after the project. The calculations reveal that 1）the tidal currents are mainly reciprocating flow，and there is only a small change in flow velocity near the wharf after the project；2）under normal weather，only the berths on the southwest side of Zhiwan Island can witness siltation，but the annual average siltation does not exceed 0.02 m，and the rest of the sea area does not encounter siltation；3）little siltation occurs at the sea areas of the project under extreme weather，and the thickness of siltation in 50 years is 0.32 m in the case of wind and waves. The main conclusions of the study are as follows：1）The project is in a place featuring clear water，little sand，weak flow intensity，and little sediment siltation；2）after the completion of the project，the overall impact on the hydrodynamic sediment environment of the surrounding sea areas is small.