The invention relates to a boiling-resistant epoxy adhesive as well as a preparation method and application thereof. The boiling-resistant epoxy adhesive consists of a component A and a component B; epoxy resin, toughener and coupling agent are mixed, and are stirred and heated, activated inorganic filler and activated inorganic flame retardant are added, polyhydric alcohol or polyhydric phenol is then added, and thereby the component A is prepared; anhydride and catalyst are mixed and heated, activated inorganic filler and activated inorganic flame retardant are then added, and after depressurization for defoaming, the component B is prepared; when in use, the component A and the component B are uniformly mixed according to the proportion by weight of 1 to 3:1, and thereby the boiling-resistant epoxy adhesive is prepared. Compared with the prior art, the boiling-resistant epoxy adhesive has high adhesive force for electronic elements, is convenient to use, and has excellent high-temperature-resistant property, high strength and good weather fastness and impregnating property, the surface properties of solidified product is excellent, and the post-solidification phenomenon caused by cracking is prevented.