The girder hoist is a kind of gantry crane specially designed for bridge construction. The girder lifting machine is mainly composed of assembled main girder, outrigger, overhead crane and so on. The components are connected by pin and high-strength bolts, which are easy to disassemble and transport. Compared with ordinary gantry cranes, the installation is convenient, fast, economical and practical. It is suitable for the construction of road and bridge units with frequent flow.