The currents in Dianchi lake were simulated by a two-dimension numerical model on wind-driven current.Numerical simulated flow field with uniform wind field and measured flows were not in agreement.Analysis of the measured winds data of the six stations around the shore of lake show that the wind directions in the six stations were not inconsistent, but the wind velocities in the zone sheltered by mountains along the west shore are 20%-50% lower than in the east shore of open water.It is evident that the wind field over lake is non-uniform due to the effect of mountain sheltering and needs to modify the wind input data in the model. According to the wind data measured, in the case of west-south wind over lake, the nonuniform wind field was artificially constructed by reducing wind velocities over lake in the zone sheltered by mountain.Using this non-uniform wind field, numerical simulated flow field was fitting better the measured flows. By comparing the mumerical simulated results between using uniform wind field and nonuniform wind field, it is obvious that the effect of mountain sheltering on the water currents in Dianchi Lake can not be ignored.In the case of west-south wind over lake, the general flow pattern in Dianchi Lake is a large anticlockwise circulation, the water velocities are low about several centimetres per second.