Due to the unreasonable dewatering scheme, the tunnel excavation was delayed for more than one year. In order to solve this problem, some pumping experiments were made. Moreover, the law of pumping rate and ground - water level reduces with pumping time- was summarized. On the basis of Tai-Si theory, dewatering calculated model was set up and the method of parameters settlement was advanced. In this case, the primary dewatering plan was revised and was very effective. Besides, the law of hydraulic jump with pumping time in various pumping rate was summarized and the reason was analyzed, which showed that the pumping rate was the main factor if the regional hydro geological condition and structure of wells are identical.