Abstract: Evaluation of the storm surge in the downstream of the tide sluice is vital to flood control and drainage from a tidal estuary. The Lixiahe district including the Sheyang River, the Huangsha River, the Xinyang River and the Doulong River situated at the north of Jiangsu Province are taken as a case study, and the tides and storm surge processes induced by "9711" typhoon are simulated by a 2D mathematic model with the nesting grids. And the storm surge characteristics of the downstream of the tide sluice are discussed, compared with those in the river mouth. The calculated results show that the storm surge vary in consistent with the tidal waves influenced by interaction of bottom friction, wave transformation in the shallow water and boundary reflections. In the downstream of the tide sluice, the high water level rises, the low water level falles, the tidal range (surges) increases, the rising tide duration is shortened, and the falling tide duration extended. And the variations of the storm surge are greater than those of tides. Furthermore, it is found that the storm surge has a significant influence on the drainage in the downstream of the tide sluice located at the estuary. The case study shows that when the water level in the upstream is as high as the sluice gate, the flood discharge of the sluice gate would decrease by 1/5 to 1/4 due to the "9711" storm surge.