Abstract: A 2-D unstable-state model of water quantity and quality on wind-driven current in Taihu Lake is established.By using the measured hydrological data,the flow and concentration fields are numerically simulated.The simulations are compared and the pollution mixing zones of main inflow rivers are obtained.Under the conditions of month average discharge of 90% assurance rate and limitation requirement of mixing zone range(3 km²),a pollutant fluxes model is used to calculate the limitations of the concentration of total nitrogen(TN).The data indicate that using 2-D unstable-state model of water quantity and quality equations to calculate showed a small measured difference in the flow and concentration fields.For the limitations of the concentration of total nitrogen in inflow rivers of Taihu Lake,the contents from Ⅰ to Ⅴ class are 0.5,1.5,3.0,4.0 and 5.5 mg·L^-1,respectively.It can provide evidence for total nitrogen standard formulation of inflow rivers.