Abstract
This paper uses mathematical model carrying out simulation research for sediment motion started by one of the dredging ways - mechanical dragging in Haihe estuary. The overall process of sediment motion being dragged is given in theory, ascertaining transport distance, exported rate, falling silt scope and returned silt quantity. Under the certain silt dragging intensity, the short time's and one year's engineering effects of lessening deposition by the mechanical dragging is given.