Introduction: TPOP-H45 is a high activity polymer polyol. The product was prepared by graft copolymerization of high activity polyether polyol with styrene, acrylonitrile monomer and initiator under the protection of specific temperature and nitrogen. TPOP-H45 is a high activity, high solid content polymer polyol. Its viscosity is low , its stability is good, and its ST/AN residue is low. The foam made of it has good tear strength, tensile strength, high hardness and better opening property. It is the ideal raw material for producing high-grade polyurethane foam.