In Fengfeng area, directional horizontal well technology was used to explore and control the aquifer of coal seam floor, in which structural water diversion was the main threat to the water inrush of Ordovician limestone confined water in coal seam floor. The thin layer (Daqing) limestone was the aquifer near to the Ordovician limestone as the coal floor, which was often used as the upper warning layer of the Ordovician limestone water. When the horizontal well of thin layer limestone encountered the structure, the stratum changed obviously, and it had more advantages compared with the Ordovician limestone in the exploration structure. The horizontal well of working face 8467 of Yangdong mine was taken as an example, the exploration structure of the horizontal well of Daqing limestone was introduced, which provided reference for mines under similar conditions.