Abstract: Yamen waterway passes through Huangmao sea.This is a main channel from Ngan Chau Lake to the sea.Results from wave climate and bedload characteristics analysis show that the high and rapid of back siltation appeared in the Yamen navigation channel in storm condition.Bedload and suspended sediment deposition in the east and west channel under the same conditions can be estimated by an empirical formula.Under the effect of simultaneously of "three main factors"(wind,wave and flow) for a whole day and night,the average siltation thickness of the east waterway is 0.15 m and the maximum thickness is 0.30 m,while in the west waterway is about 0.30 m and 0.62 m,respectively.The possibility of sudden siltation and ranges in the western channel are much greater than the eastern channel.This is due to the west waterway is located in the open sea of Huangmao Sea.However,the east waterway passes through many islands which are covering against the storm.In a period of development of Yamen navigation channel,the sudden siltation in the west channel under heavy storm conditions should be paid a special attention to sudden sileation during the development of Yamen waterway.