To meet the need of project development in Taozi Bay,we carry out a study on the hydrodynamic sediment problem.Firstly,according to the in-situ hydrologic sediment data and wave data in Taozi Bay and nearby,we analyze characteristics of tide,tidal current,wave,sediment concentration,seabed material,etc.,and give design water levels and wave characteristics of different return periods in the mouth of Taozi Bay.Secondly,we analyze the coastline change and seabed evolution based on bathymetric charts measured in different years.Finally,we calculate and analyze the sediment movement.The conclusions are drawn as follows:Taozi Bay belongs to a typical arc coast with little sediment source,and sediment concentration under normal weather conditions is very small.The tidal current is dynamically weak，and the wave action cannot start the sediment movement and transport of the bed.The sediment movement under wave action is dominated by the transverse transport,and longshore sand transport is weak.Sediment movement is generally weak in Taozi Bay and the beach remains stable for years.