Back silting easily occurs after channel excavation,and the study on the amount of back silting is particularly important for the later maintenance of the channel.Taking the back silting of the approach channel of Gaolan Port as a research case,and based on the historical evolution of the seabed in the Huangmao Sea area,we analyze the source of channel sediment in Gaolan Port area,and study the characteristics of sediment erosion and sedimentation near the channel.The research reveals that the seabed in the cross waters where Gaolan Port locates has always been in a state of sedimentation in recent years.From 1977 to 1989,the average sedimentation intensity was 3.42 cma,and from 1989 to 2003,the sedimentation rate slowed down to about 0.86 cma.The annual siltation amount of the waterway in Gaolan Port area consists of two parts:perennial siltation and sudden silting caused by typhoon;obvious sudden silting occurs once or twice a year,and the amount of sudden silting is generally 30% to 50% of the annual silting amount,the thickness of sedimentation is 0.32～0.60 m,and the magnitude and distribution of sudden sedimentation volume are related to the typhoon path and intensity.The research results may serve as reference for determination of the time and frequency of channel maintenance.