Abstract: Taking the construction of ZKxx3 hole in the first stage of grouting reconstruction of no. 2 coal-ornite aquifer in north well 9400 dongpang mine as an example, this paper introduces in detail the construction design, drilling technology and main technical measures of directional drilling for horizontal branch hole. Practice proved that the directional drilling technology as much as possible to probe into the ordovician limestone aquifer fault and collapse column structure of the area of the water channel and rich water, advance grouting filling the upper ordovician limestone dissolution gaps and cracks, jig faults and tectonic weak section, expand the reinforcement area, to realize the local management to the ground area management by underground coal floor Mr Grey water disasters, from the advanced detection to dig governance before, met the area ahead of the prevention and control of water disasters objectives in time and space, has achieved remarkable economic and environmental effects.