Abstract: Based on the two-dimension adlittoral non-invariablenes flow control equation of lakes,a hydrodynamic model of lakes was built up.According to the real situation of Tianjin Yuqiao Reservoir,the model simulated the stream fields for import water period and no-import period.The simulated results indicate that when the stream field begins steady,there is a steady main flow channel from the east part of the lake to the west part.The simulation with initial out flow velocity has been done and the simulation results show that the stream fields have a good relationship with the pollutants distribution.