Terrain is an important factor influencing the velocity and the distribution of water current in lake.It decides the substance transpo rtation and dif fusion in lake water.This induces the study on the influence of the reclaiming of Mashan Dist ricton wind-driven current to be impo rtant to know the change of water quality in Meiliang hu Bay.The influences of the reclaiming of Mashan districton the wind-driven current were discussed on the base of the part 1 and part 2 of thre three-dimensional numerical experimenton hydrody namics in Lake Taihu, China.The results showed that the reclaiming in Mashan district had fewinfluences on the layer water current except the conversion layer water current.As to the conversion layer, it has great influences on velocities and directions of the conversion layer water current and the vertical averaged water current.It decides the structure of the circulation formed by the vertical averaged water current near the Mashan District.In particular, in case there blows SW wind these kinds of influences are very strong, e.g.the reclaiment changed the flow direction and the location of the g reat-scale circulation in the west partof the lake, and rest rained the water in the decreased the net water exchange rate between Meilianghu Bay and the open area of the lake by the reclaiment.Especially, in the case of SW, notonly about 98% of the net water exchanges were cut down, but also the water exchanges on the layer blow surface layer, middle layer and the layer above the bottom layer were cutdown in a relative high percentage.