Due to the long service life and the influence of surrounding rock ground pressure, the Dongfeng well hydrological observation hole ruptured and leaked at No.2 coal seam, and the maximum water output reached 120 m3/h, which poured into the main mining roadway. Through analysis, the damage formed the water conduction channel between Ordovician limestone water and production roadway. By using imaging detector to find out the internal structure of borehole and the damage position of pipe wall, putting steel balls and other water-blocking materials into the hole, and improving the airbag water blocking device, the grouting pressure of sealing hole reached a reasonable value of 4 MPa, the cement slurry solidified well, and the underground water outlet point was completely sealed, which successfully eliminated the safety hazards.