Abstract: Because of construction of the world famous.Three-Gorge Project,the local turbulent flow,compared to the original,has been changed greatly.The variation of hydrodynamics results in change of water environment.Based on the features of hydrodynamics and contaminant transportation of the water body affected by constructing the Three-Gorge Project's first- and second stage-cofferdam,this paper establishes a 3-D hydraulic and water quality model.The results of simulation indicate that there is a pollution zone in the area close to the discharge outlet,but the polluted range and the contaminant concentration is not big.Most of the water body is not affected and the water quality is close to that of inflow.