The invention belongs to the technical field of food safety detection, and particularly relates to a method for authenticating plant oil and waste food oil through SIFT/MS. The method detects 28 components, namely, furan, acrylamide, furfural, 2-amyl furan and acrolein which are produced by heating and inducing grease, external pollutants including citral, limonene, diallyl sulfide, m-cresol, 4-isopropyltoluene and methyl chavicol, oxidation decomposition aldehyde products including heptanal, octanal, hept-2-enal, 3-hexene aldehyde, trans-2-octen-1-al and (E, E)-2- decadienal, oxidation decomposition acid products including acetic acid, propionic acid, butyric acid, valeric acid and caproic acid, and other oxidation decomposition products including acetone, butanone, 2-heptanone, 1,3-propanediol, 1,4-butyrolactone and propyl propionate, thereby authenticating plant oil and waste food oil. The method saves reagent cost, is free of advanced concentration, column separation and standard products, and has the advantages of being high in sensitivity, simple, rapid, accurate and the like.