The invention discloses a steel box girder assembling positioning structure, a supporting structure and a linear control method of a bridge and relates to the technical field of steel box girder construction. The steel box girder assembling positioning structure comprises an elevation limiting component and a horizontal limiting component; and the horizontal limiting component and the elevation limiting component are configured to be fixedly arranged at the top of a bed-jig. The elevation limiting component comprises an elevation adjusting piece with a matching surface; the matching surface isused for being attached to the bottom of a steel box girder; the horizontal limiting component comprises a first limiting piece; and the first limiting piece is used for abutting against the side wall of the steel box girder and can limit the displacement of the steel box girder in a first direction. According to the steel box girder assembling positioning structure, by using the elevation adjusting piece, the displacement of the steel box girder in the vertical direction is limited; and moreover, by arranging the first limiting piece, the displacement of the steel box girder in the first direction is limited. During hoisting, only by enabling the bottom of the steel box girder to be attached to the matching surface and enabling the side wall of the steel box girder to abut against the horizontal limiting component, the hoisting of the steel box girder can be finished.