Dongshui harbor is located in Dongshui lagoon of Chengmai Bay,Hainan Island.Aiming at the development and construction of deepwater Dongshui harbor,we study the hydrodynamic sediment characteristics of Chengmai bay and Dongshui harbor based on the analysis of natural conditions,beach evolution,suspended sediment movement and coastline change by remote sensing,and numerical modeling of tidal current and sediment.The results show that Dongshui harbor in Chengmai Bay possesses favorable conditions to be constructed into a deep water harbor as far as hydrodynamic sediment conditions are concerned.