Abstract: According to the hydrological geological conditions of certain open mine and the results of groundwater pumping experiment, a reasonable seepage numerical model was set up with MODFLOW, and the process of the confined water level descending with the time was studied. In addition, a calculation of the example was made, which indicated that the calculated data fit the observation ones well. Furthumore, a forecast study was conducted to provide a theoretical guide to the groundwater descending design in the excavating for the open mines.