The upper Jurassic coal seam resources in the northern part of the Datong Coalfield were nearly exhausted, in recent years, most of the mines was diverted into the exploitation of carboniferous coal seams, with the increase of mining depth, the threat of cambrian-ordovician Karst water to coal seam was increasingly prominent. Although the upper carboniferous coal seam in this area with low belt pressure and a large interval (about 80~100 m) between it and the Ordovician strata, the water gushing event of Mining No. 5(3-5) coal seam to conduct Karst water occurred due to the influence of structure Karst water gradually became an important water-filling source for the exploitation of carboniferous coal seams. The Karst water level in this area changed greatly, and there was a lack of systematic hydrogeological work at the regional level. It was of great significance to the prevention and control of floor Karst water in carboniferous mines.