The invention discloses a novel construction method for an efficient fabricated steel-concrete composite beam, which belongs to the technical field of bridge construction. The method comprises the following steps of adopting a steel beam, whose top end is connected with a rubber sealing strip and a ribbed plate, as an assembling platform; laying a precast concrete bridge deck slab on the rubber sealing strip, wherein a channel is formed in the bottom end of the precast concrete bridge deck slab; and injecting a high-strength grouting material into a grouting channel, which is enclosed by the steel beam, the rubber sealing strip and the precast concrete bridge deck slab, so as to form the steel-concrete composite beam. According to the novel construction method for the efficient fabricated steel-concrete composite beam, disclosed by the invention, problems that the combining surface of the steel-concrete composite beams is corroded, concrete is cracked, the quality of post-poured concrete is hard to problem and so on due to machining a steel-concrete connecting piece and casting jointed concrete in place are effectively solved; the on-site working efficiency is increased while the construction quality is guaranteed; and the novel construction method is environment friendly and exerts good economic benefits.