In order to study Longwan coalfield ordovician limestone series top rock stratum waterproof performance and the feasibility of the grouting reinforcement and reconstruction， top ordovician limestone lithology combination of relative water-resisting layer， rich water distribution characteristics and top ordovician limestone Artificial relative water-resisting layer segments transformation were discussed， conventional rotary drilling technology at home and the technical features and practical effect of directional drilling technology were introduced. The result showed that after the use of top ordovician limestone 50 m relative impermeable layer， the proportion of No. 15 coal seam threatened by baseboard ordovician limestone high pressure water obviously reduced， compensated mining recoverable reserves could meet the needs of the mine.