Abstract: In this paper, based on a large number of actual survey data over the years and combined with previous research results, the sea bottom topography and geomorphology of the South Yellow Sea are studied. The results show that the sea bottom topography of the South Yellow Sea is classified into 6 units. In the western South Yellow Sea, there are underwater mud wedge terrain area of east Shandong Peninsula, gentle-dipping terrain area in the Haizhou Bay and tongue-shaped terrain area off the coast of Jiangsu Province. In the middle South Yellow Sea, there are the terrain areas of shallow plain and the Yellow Sea Trough. And there is slope-trench terrain area in the eastern of South Yellow Sea. The sea bottom slops down gradually from west, north and east to the center and the south-east. The western slop is smooth terrain, but the eastern slop is relatively steep. There are 11 geomorphologic types on the sea bottom of the South Yellow Sea, dominated by accumulation, erosion-accumulation type of geomorphology in the west of the central line of the Yellow Sea Trough Valley, and in the east, dominated by tectono-accumulative geomorphology. The evolution of sea bottom topography and geomorphology of the South Yellow Sea is mainly controlled by regional structure, sea level fluctuation, ocean hydrodynamics and material sources.