The invention discloses epoxy phosphate modified thermoset acrylic resin. The resin is characterized by comprising a first component, a second component and a third component, wherein the first component comprises dimethylbenzene and butanol; the second component comprises methyl methacrylate, methyl isobornyl acrylate, iso-octyl acrylate, acrylic acid, hydroxyethyl acrylate, butyl methacrylate, butyl acrylate, epoxy phosphate and peroxide benzoic acid tert-butyl ester; the third component comprises dimethylbenzene and peroxide benzoic acid tert-butyl ester. Compared with common thermoset acrylic resin, the resin has the advantages that the quick ultraviolet (QUV) resistance time is long, and the weatherability is excellent; the viscosity is low, the solid content is high, and the gloss fullness degree of a paint film is excellent; the hardness is high, and the resin can be applied to metal shell original-factory stoving varnish of a high-grade automobile; the adhesive force is great, and the adaptability to a substrate is higher.