The invention relates to a preparation method of plugging composite material polyurethane elastomer used in coal mines, and the method comprises the following steps: taking modified nano titanium dioxide, polyether polyalcohol, toluene diisocyanate and the like as raw materials; synthesizing respectively component A yellow transparent liquid product and component B white opaque liquid product in a reaction kettle test jar under the state of vacuum, heating and stirring; stirring and blending with the ratio of 4:6 when in use; spraying or brushing the plugged object; and solidifying after drying. The invention has the advantages of good plugging effect, good cohesive force, high rigidity, high temperature and low temperature resistance, aging resistance, good elasticity, shock absorption, acid resistance, oil resistance, water resistance, anti-static ability, tight padding, good insulation and good compactness; the invention can rapidly plug leaking water, leaking gas, leaking oil and cracks; the invention has rapid drying speed, after plugging by synthesization of component A and component B, drying and solidification can be completed in 120 min, and the thickness of the solidification layer can reach 4mm; the preparation method has short process flow and reasonable ratio, and can be applicable to building, petroleum and chemical industries.