Abstract: Distribution and transportation of surface sediments are analyzed in this paper based on grain size data. Results show that: (1) bottom sediment particle is generally getting finer from land to sea. Within the water depth of 5 m, coarse sand and coarse-medium sand dominate; (2) the sediment is mainly medium sand and fine sand in the area between 5 - 10 m in water depth; (3) fine sand dominates the area of 10 ~ 12 m in depth, while in the area deeper than 12m, silt and clay dominate. Waves play a key role in initiation of sediment moving. Under the action of wave flow, sediments are easy to start moving. Longshore sediment transportation is limited, but remains in a relatively stable status. The sediment transport is consistent with the hydrodynamic and topographic features. At present, the sediment is under a status of dynamic balance and no large-scale erosion and/or deposition is expectable.