Abstract: Aiming at the difficulty of sealing holes in approximate horizontal seam, a new type of automatic water absorption blocking device is developed, based on “two blockages and one injection method”, by installing expansion blocking plugs at both ends of the sealing device and leaving a grouting section in the middle. It can simply achieve effective plugging of approximate horizontal borehole grouting, grouting and plugging are synchronized. The combination of high expansion resin with high strength water swelling rubber ensures the grouting stop effect and increases the grouting pressure from 1.2 MPa to 1.5 MPa. The slurry can penetrate into the internal cracks of the coal body around the borehole under the action of pressure, which can effectively improve the density of the slurry, avoid the problem of air leakage passage formed by the drying shrinkage of the cement slurry along the borehole in the approximate horizontal coal seam, and ensure the sealing effect. Through the field test, the gas extraction concentration of the automatic water absorption and expansion sealing device increased by 19% to 23% compared with the common grouting sealing method.