Based on the observed data of hydrological sediment and the depth of terrain for many years in Oufei shoal,this paper analyzes the characteristics of the hydrodynamic sediment and the evolution of terrain erosion and deposition.The results show that the current in the study area are non-formal half-day shallow-sea tides,and K of the sub-stream ellipticity of each vertical line is between 0.00 and 0.20.Therefore,the current is dominated by reciprocating currents,and the distribution of sediments shows a gradual increase in the outer seaward direction.The sediment concentration in the tidal period is significantly greater than that in the mid-tide and the tidal waves.Through calculations of the scouring and siltation of Oufei shoal in recent decades and related cross-sectional analysis,it is known that the tidal flats in Oufei shoal are generally at a slightly high silt height.Unlike the tidal flat area,the underwater shoal area of Oufei shoal was from 1987 to 2010,and the average annual erosion rate was 0.008 to 0.02 m,showing a state of stable and slightly scouring.