Abstract: Close to the South channel of the Yangtze River estuary,the main channel to transport sediment,the east shore of Nanhui becomes an important position for sediment silting. It has an favorable condition of the shore and sediment supply for reclaiming,and now is a key area in Shanghai reclamation plan. Shanghai has already started a reclamation project on the east shore of Nanhui. The reclamation will move the sea line,which can bring about the change of the hydrodynamic condition. A 2-D tidal flow mathematics model is set up to predict the change and discuss the influence of the project on the water area surrounded.