The invention discloses a transverse reinforcing device for a corrugated steel web combination beam. Vertical steel plates of H-shaped steel is adopted as corrugated steel webs, flat steel plates are fixed at the opposite inner sides of the corrugated steel webs, and a transverse connecting structure is arranged between every two adjacent corrugated steel webs. Compared with a transverse connecting structure of a traditional combination beam, the transverse reinforcing device has the advantages that the steel webs can achieve higher plane stiffness and buckling strength without needing to be welded with stiffening ribs and the higher shear-bearing capacity in very small thickness; the transverse stiffness of the steel webs is further improved through the combination of the flat steel plates and the corrugated steel webs; transverse restrain of the combination beam is reinforced through threaded steel rods, and therefore the lateral deformation-resisting capacity of the combination beam and the overall torsion-resisting capacity are significantly improved; compared with traditional angle steel welding connection, the steel rods are fixedly connected through the threads, and the advantages of being easy to operate, fast to construct, convenient to assemble and disassemble and the like are achieved.