The invention discloses an adhesive for steel-aluminum bonding. The adhesive comprises, by weight, 40-45 parts of E-type epoxy resin, 15-20 parts of polysulfide rubber, 5-10 parts of polypropylene glycol diglycidyl ether, 5-10 parts of phenyl glycidyl ether, 5-10 parts of polyol and 90-100 parts of microcapsules, and the adhesive for steel-aluminum bonding is used for crushing the capsules. The adhesive for steel-aluminum bonding has a good bonding effect, and has very good mechanical strength and stability; and a solvent used in the invention is nontoxic, so the adhesive is safe to use, has very good comprehensive properties, and can be widely applied to steel-aluminum bonding.