The invention discloses a preparation method of high-molecular graphene modified epoxy resin, and belongs to the technical field of epoxy resin. The high-molecular graphene modified epoxy resin is prepared from the following components in parts by weight: 5-10 parts of graphene, 60-80 parts of epoxy resin, 15-20 parts of n-butyl polyacrylate, 5-9 parts of phthalic anhydride, 3-6 parts of azodiisobutyronitrile, 2-4 parts of diallyl phthalate, 5-15 parts of polyglycidyl methacrylate, 28-43 parts of diglycidyl resorcinol ether, 17-29 parts of urea-formaldehyde melamine resin, 10-15 parts of EDTA,13-15 parts of CTBN, 6-13 parts of an organosilicone coupler, 5-8 parts of aminomethyl propanol, 60-90 parts of water, 4-12 parts of carbon powder, 13-15 parts of aluminum silicate powder, and 10-15parts of antimonous oxide. Through combination of the graphene and the epoxy resin, the advantages of the graphene and the epoxy resin are considered, the heat conducting, toughening and abrasion resisting performance of a compound is improved, and the purpose of improving the weather resistance of the compound is achieved.