Abstract: To solve the problem of low gas extraction rate and gas concentration from the outside of coal wall, prevent external air from mixing with gas through pores and cracks in the coal wall to increase the concentration of gas, this paper proposes a method: spraying a solution material to the coal wall and forming a thin film with uniform and dense thickness, which can be used to seal the cracks on the surface of coal seam, reduce the permeability coefficient of coal seam surface greatly, so as to accelerate gas extraction and obtain higher concentration of gas. By screening and comparing various possible materials, and referring to the purpose and requirements of the experiment, the acrylic silicon modified polymer waterproof coating and JS09 polymer waterproof coating were selected. The properties of air tightness, strength and ductility of these two materials were studied. The results show that the polymer waterproofing coating modified by silicon acrylic acid meets the requirements and can be used as an alternative material for further experiments.