Abstract: Exploration and drainage drilling has been widely applied in underground coal mine, which provides technical guarantee for coal mine safety production. In order to solve the water hazard problem of floor limestone aquifer in the mining of "Group A Coal" in Zhangji Coal Mine, the directional drilling technology was introduced into the floor water exploration and drainage drilling, and the success was achieved. The directional drilling project in -600 hydrophobic roadway was constructed to control the water hazard of floor limestone in 1612A and 1613A working faces. At present, 15 boreholes have been constructed in the water hazard control projects of drainage roadway in these two working faces. With a total footage of 5480 m and two important water outlets identified, the problem of water hazard detection of working face floor limestone can be effectively solved. The technology of water exploration and drainage of working face floor limestone based on directional drilling in Zhangji Coal Mine has been formed, which can be widely applied in similar mines.