Abstract: Group A of coal seam in Gubei Coal Mine is seriously threatened by limestone water hazards. Used the technology of directional long drilling along the seam to explore the limestone aquifer in the floor of the working face. According to formation characteristics, studied the construction methods and key technologies of directional drilling opening section, directional inclination section and directional stable unloading section. And directional exploration drilling was carried out in 13321 and 13121 working faces for practical verification. The results show that directional long drilling technology can realize the exploration of full coverage of aquifer in working face floor, with high rate of drilling in the target horizon and long distance in one exploration, which can reduce the amount of routine drilling work and bring significant economic benefits.The successful implementation of the technology solved the problem of limestone water hazards in Gubei Coal Mine.