Abstract: In the process of ascending mining, in order to research the influence of lower coal mining on its roof aquifer and the upper coal roof aquifer, and taking targeted water prevention and control, based on the analyzing of mine hydrogeological conditions, we established three-dimensional numerical model by FLAC^3D, forecasted the scope of "two belts" by lower coal mining, and analyzed threat level of the lower coal mining for compound aquifer. Results showed that the scope of "two belts" by lower coal mining was less than the distance between two coal seams, only under the influence of its roof aquifer; there was no threat of the upper coal roof aquifer; and then the work of water hazard prevention was determined. Through the analysis, the scope of "two belts" by lower coal mining based on numerical simulation forecasting can be taken as water prevention and control measures under the condition of ascending mining.