Construction method using guide girder and gantry crane to mount prefabricated box girders

The invention discloses a construction method using a guide girder and a gantry crane to mount prefabricated box girders. The method includes the steps of firstly, measuring and positioning; secondly,mounting the guide girder; thirdly, mounting the gantry crane; fourthly, mounting one box girder, wherein one end of the box girder is hoisted on the slide-wheel trolley of the guide girder, a girderconveying vehicle move backwards to move one end of the box girder to a cover girder end through the slide-wheel trolley, the box girder is hoisted away from the girder conveying vehicle and the guide girder through a crane at a bridge abutment and the gantry crane on a cover girder after the box girder is longitudinally in position, and the crane and gantry crane electric hoist are used to transversely move the box girder out of the guide girder to reach a mounting position and place two ends of the box girder on supports; fifthly, completing the parallel mounting of multiple box girders between the bridge abutment a