Operation of the Hiree Gorge Project will change the hydrological processes and affect the ecosystem of lake wetland.The two time periods, i.e.water storage after flood season and water emptying before flood season, with highly changed water regime are selected to evaluate the effects of the Three Gorge Reservoir regulation by using the hydrodynamic method.The lake water levels and discharge variations are computed under the different regulation c￡ discharge values.Gombined with lake level variations and the elevation-area curve, the wetland exposure area are also analyzed.Results show that lake level of the Lake Poyang (at Duchang Station) would decrease 0.09-1.11m for steady flow condition if the discharge of Yangtze river decreases 1000-7653m³/s after flood season, whereas lake level will increase 0.15-0.94m if the dischaige increases 1000-6500m³/s before flood season.The effect of Three Gorge Reservoir on lake levels varies significantly from northern to southern part of the lake, which are depended on the hydrodynamic cainectivity conditions.