The invention belongs to the technical field of mining materials, and particularly relates to a support modified polyurethane hole sealing material. The support modified polyurethane hole sealing material is prepared by the following steps of using magnesium chloride as the raw material, preparing a magnesium chloride mixed solution, mixing with a sodium carbonate solution, filtering, collecting filter cake, washing, drying, calcining, mixing with sepiolite and fly ash, grinding, and screening, so as to obtain ball mixing mixed powder; heating with acrylic acid and the like, filtering, obtaining filter slag, washing, drying, grinding and screening, so as to obtain modified particle; dispersing with polyether polyol and the like, so as to obtain a component A; mixing hexamethylene diisocyanate and the modified particle, so as to obtain a component B; in the use process, mixing the component B and the component A, foaming, curing, and forming, so as to obtain the support modified polyurethane hole sealing material. The prepared support modified polyurethane hole sealing material has the advantages that the elasticity is small, the easiness in compression is avoided, and the easiness in deformation and creepage is avoided in the use process; after injecting into a drilled hole, the effective support function is realized; the action time of plugging of the material is long, the easiness in shrinkage and cracking of the material self is avoided, and the gas extraction efficiency of the mine well is effectively improved.