In recent years, water from the bottom plate of North China coalfields has surged through the perpendicular hidden water-conducting channel, resulting in flooded wells, flooded surfaces and other water damage accidents from time to time. The Xinji No.2 mine is influenced by the huge thick pushing overburden, and the three-dimensional seismic survey and drilling survey can not identify the perpendicular hidden water-conducting channels such as faults and trapped columns, and the water damage of the coal seam floor with high pressure-bearing ash aquifer seriously restricts the safe mining. The practice showed that the water source of the coal seam floor underflow in Huainan Mine was mainly from the Karst water of the Ordovician limestone, and the underflow channel is the hidden fault or collpased column. The mine combined the special geological and hydrological geological conditions with the special geological and hydrological conditions, and formed the key technology to prevent and control the water damage of the high-suppressing limestone underflow from the prevention and control concept, target layer position, borehole spacing and effect evaluation, which was of great significance in similar mines.