Along with propulsion of a working face in an underground coal mine, drilling is needed for gas drainage and water drainage. Spraying orifice and water burst often occur in the previous drilling process, coal or high-pressure water sprayed by spraying orifices may cause severe threats to personal safety of drilling workers. According to the technical scheme, a low-cost spraying orifice preventing automatic sealing device is applied. When the drilling is performed normally, no deformation occurs in a rubber drum in the sealing device, a drill rod works normally, and coal dust and water generated by drilling can be discharged out of the orifices normally; when water burst or gas burst occurs, the high-pressure water or coal blocks have impact on the rubber drum, the rubber drum is subject to plastic deformation, gaps between the drill rod and the rubber drum are blocked, the drill rod is locked, the effect of automatic sealing is achieved, and the goal of protecting personal safety of the drilling workers is achieved. The sealing device is simple, novel and unique in structure and simple and convenient to use and operate, is a great innovation in the field of coal underground coal mine drilling and is remarkable in economic effect.