Abstract: The paper, according to the geological and hydrogeological conditions as well as karst development, discusses the damage height in overlying strata and the size of water-proof coal and rock pillars based on the analysis of the structure of overlying strata. Besides, it makes analysis on mining safety under Karst lakes and thick limestone aquifer. And it also studies the influence of coal seam mining on Karst lakes from the perspective of movement and deformation. Results show that the height of water-conducting crack zone is 66.55 m, above which, there are aquifuge P₂l⁵, aquifuge T₁f^1-1 and aquifuge T₁f^2-2, and the water from Karst lakes as well as from limestone in Changxing and Feixianguan respectively will not go in coal mines. Therefore, working under mines is safe and will not lead to the collapse of karst water level in lake, which proves that it hardly leads to secondary geological hazards. Therefore, mining under Karst lakes and thick limestone aquifer is safe.