The invention discloses a GMS-based (
groundwater modeling 
system) forecast method for ground 
water seepage fields at different mining levels of a mining area. The method comprises the steps that through performing analytical investigation on hydrogeological conditions of an area, boundary conditions and water containing bodies are generalized, ground water runoff conditions are analyzed, and coefficients of each 
source sink term are determined; the GMS is adopted to perform finite difference grid division on a 
simulation area, an initial water head is determined based on the 
water level of an observation well, hydrological parameters of each 
simulation sub-area are determined based on a pumping test and the provided data, hydrological module types of the 
source sink terms in the area are analyzed, assignment is performed on a corresponding hydrogeological map layer by combining the determined 
source sink term coefficients, and then a subarea map of the osmotic coefficients at different mining levels is obtained; prediction models for ground 
water seepage fields of a mining area are established based on GMS, and the 
observation data is utilized to adjust the hydrogeological parameters of the models, and finally, 
simulation is performed by combining with the 
discharge capacities at different mining levels to obtain the ground 
water seepage fields at different mining levels. The method has the advantages of convenience in operation, excellent three-dimensional 
visualization function and reliable result.