Based on considering the variation of vertical coefficient from bottom to surface, a quasi-3D numerical model was put forw ard to calculate the wind-driven current, and was applied in Taihu Lake under steady and unsteady winds, respectively, the resuls were satisfactory.Comparitive studies showed that the influence of the variation of vertical coefficientof eddy viscosity along the water depth is lit tle to the computation resuls of surface elevation, but it is great to the computation results of the velocity profile and the bed shear-st resses.Therefore, it is needed to consider the variation of vertical eddy viscosity coefficient to simulate the 3D wind-driven circulation in lakes for better simulation.