The invention relates to a 4,4'-bis(2,4-diamidophenoxy)diphenylsulphone high-temperature-resistant epoxy adhesive and a preparation method thereof. The 4,4'-bis(2,4-diamidophenoxy)diphenylsulphone high-temperature-resistant epoxy adhesive is composed of a component A and a component B in a mass ratio of 1:(1-2), wherein the component A is a copolymer prepared by reacting 4,4'-bis(2,4-diamido phenoxy)diphenylsulphone and epoxy resin; and the component B is a homogeneous-phase transparent solution with the solid content of 15-30%, which is prepared by reacting 4,4'-bis(2,4-diamidophenoxy)diphenylsulphone and aromatic dibasic acid anhydride in a strong-polarity non-proton organic solvent and diphenylsulphone. The preparation method comprises the following step: evenly mixing the component A and the component B in a mass ratio of 1:(1-2) at room temperature. The preparation technique is simple; and the adhesive has excellent comprehensive properties, can be widely used for bonding steel, copper, aluminum or any other metal with ceramic, glass, resin-base composite material or any other substrate, and has favorable industrialization prospects.