The invention provides a polyurethane long-distance rapid fixed-point hole sealing device for underground drilling of a coal mine. The polyurethane long-distance rapid fixed-point hole sealing device comprises supporting legs, a material injection barrel, a barrel cover, a pressure air connection pipe, feeding funnels, a powerless pipeline mixer, a first polyurethane foaming bag, a second polyurethane foaming bag, a pressure measuring or extraction pipe, a first material injection pipe, a second material injection pipe and a slurry injection pipe, wherein the barrel cover is horizontally arranged at the top of the material injection barrel; the material injection barrel is internally vertically provided with a separation plate for separating the inner part of the material injection barrel into a material storage chamber a and a material storage chamber b; the pressure air connection pipe and the two feeding funnels are arranged on the barrel cover; the upper end of the powerless pipeline mixer is arranged at the center of the bottom of the material injection barrel; and an inlet of the powerless pipeline mixer is communicated with the material storage chamber a and the material storage chamber b. The invention further discloses a hole sealing method. With the adoption of the polyurethane long-distance rapid fixed-point hole sealing device provided by the invention, the labor intensity of workers can be greatly alleviated; the polyurethane long-distance rapid fixed-point hole sealing device has the advantages of light weight, convenience for carrying, simplicity in operation and the like; after hole sealing work is finished, a plastic thin film in the material injection barrel is removed to finish the work, so that the procedure of washing the material injection barrel is avoided and the device is convenient and rapid.