Taking a sea-crossing bridge as an example,considering the demanding requirements for offshore prefabricated bridge construction on the construction site and environment,a 100-meter-span erection technology is proposed,and a 100-meter offshore prefabricated segmental bridge erection machine was studied and designed.The bridge erection machine adopts segmental assembly technology in the erection of 100-meter span,improves the construction efficiency,meets the special needs of long-span bridge engineering,and provides a feasible solution for the construction of offshore bridges.