The No.1 harbor basin of the Tongzhou Bay port area is built at Yaosha，which is on the southern edge of the radiation sandbar，and siltation after channel excavation of the harbor basin is the focus of engineering design.In design，by studying the natural features of the engineering sea areas such as tidal current，wave，sediment，and substrate，and analyzing primary factors affecting siltation，we propose some countermeasures，such as layout of sand barriers，determination of the depth reserved for siltation，maintenance dredging，and draft control.The research reveals that since the No.1 harbor basin is built on a shallow silty beach，channel excavation of the harbor basin will result in siltation.However，the No.1 harbor basin has its entrance facing south and is well sheltered，so there is only a low risk of sudden sedimentation.In the first stage，we can cope with siltation by trial dredging in the harbor channel，reserving sufficient water depth for siltation，equipping an efficient dredger and controlling draft.In the future，we can consider whether to build a sand barrier or not by combining the results of siltation observation，the difficulty of maintenance and the influence of ships’ entering and leaving the harbor basin.