Based on the detailed analysis of site engineering geological and hydro-geological conditions for the proposed project Nanchang International Finance Center high-rise building, the dewatering design of this fundamental pit is proposed， in accordance with the surrounding environment as well as those pit design elements and so on. The three-dimensional numerical simulation model of groundwater for dewatering is also established. Using the three-dimensional groundwater numerical simulation software, Visual-modflow, the site is meshed into grid and the dewatering model is built under different well numbers and space. Al last, an optimal program (10 pumping wells for each pit and well equaling space) for this pit has been determined. It is also to simulate the water level vs. time during the dewatering. This does not only provide a strong basis for the optimum design of the foundation pit dewatering, but also provide a scientific basis for decision making to the underground construction.