The invention discloses a polymer spray material for sealing coal seam gas. The material is prepared from a component A and a component B, wherein the component A is prepared from water glass and an additive, and the additive accounts for 0.05%-35% of the mass of the water glass; the component B is prepared from isocyanates, a thickening time control agent and a plasticizer, the thickening time control agent accounts for 0.001%-17% of the mass of the isocyanates, the plasticizer accounts for 0.5%-30% of the mass of the isocyanates, and the volume ratio of the component A to the component B is (1:10)-(10:1). With adoption of a low-cost water-soluble silicate material, the cost of the material is significantly reduced, and the material has a broad application prospect; meanwhile, with adoption of a non-combustible water-soluble silicate material, flame retardancy of the polymer spray material is improved, and the polymer spray material is more applicable to underground coal mines.