Due to the climatic drought and a large amount of groundwater drainage, environmental geological problems such as hydrological circulation disorders, soil desertification and grassland degradation are common in open-pit coal mining areas. This study takes the Yimin open-pit coal mine area in Hulun Buir Grassland as the research object. Based on the investigation and analysis of the groundwater-lake system, this study combines hydrological, meteorological and remote sensing image data to construct the mathematics of the groundwater-lake response mechanism in the mining area. The model is used to predict and analyze the impact of mine development on lake in the area. The results show that the number of the group of lakes has changed from 5 to 2, and the total area of lakes has shrunk from 6.94 km² to 1.12 km² in the past 35 years of coal mining. The groundwater-lake interaction in the mining area has evolved from the type of natural groundwater recharge lake to the one of lake recharge groundwater. Based on the principle of water balance, the mathematical model of the groundwater-lake response mechanism in the mining area is established. Based on the analysis of the coupled mathematical model of groundwater and lake, it is found that under the condition of limited fluctuations of climatic factors and stable development of the mine, the largest chedaminor lake in the study area will shrink to 0.56 km² when the mine would be closed (in the year of 2045).