The invention provides a rectifying device used for mounting elevated frames and bridges and a rectifying method of the rectifying device. A bridge box girder is jacked through a vertical jack in a jacking unit, and the vertical jack in the jacking unit is horizontally pushed to move along the direction perpendicular to a jacking sliding axis through the rectifying device in the jacking unit after the bridge box girder is jacked up, so that the bridge box girder can be rectified in real time during the course of pushing the bridge box girder, and a bridge line is ensured not to generate deviation on the basis of not reducing construction efficiency.