Abstract: Tidal current in Xiashimen water area is a kind of clockwise whirl current. Based on analysis of tide, tidal current, wave and sediment, the distribution of suspended sediment concentration was set up. According to channel deposition characteristic under whirl current, the paper estimates deposition amount of channel which is planned to be excavated. Considered from channel deposition and its maintenance, it is feasible to excavate twenty thousand to thirty thousand tone channel outside of Xiashimen entrance.