Abstract: A high resolution bathymetric survey has been carried out using the Sonic 2024 Multi-Beam Sounding System in the Dongfang Wind Farm offshore Hainan Island. A lot of images such as the bathymetric charts, 3D submarine geomorphologic maps etc are made from the survey data. The water depth depth of the study area ranges between 8 to 32 meters and it is deeper in the west rather than in the east. As the results, the terrain is higher in the northeast. There are two submarine geomorphological features in the study area, a U-shaped erosion valley and two sand wave areas. The water depth of the U-shaped valley is deeper than any part of the study area. The topography of the valley bottom is relatively flat, and there are no big relieves. The sand waves are widely distributed and belong to large and giant sand waves. The crests of sand waves are basically in E-W direction. But there are differences in spatial distribution patterns and geometric parameters between the two sand wave areas.