A bridge maintenance device comprises a cleaning vehicle and a box body which is fixedly mounted on the upper side of the cleaning vehicle; a first transferring groove, a sliding connection chamber and a second transferring groove are respectively arranged in the inner wall of the cleaning vehicle; a first conical pulley is rotationally arranged on the interior top wall of the first transferring groove; a transferring column is fixedly mounted on the end surface of the top of the first conical pulley; the transferring column is connected with the cleaning vehicle in the form of normal runningfit and upwardly extends and penetrates into the cavity of the box body; the end surface of the top of the transferring column is connected with a circular ring, which is fixedly mounted on the interior top wall of the cavity, in the form of normal running fit; and an oblique angle plate, which is connected with the transferring column in the form of normal running fit, is fixedly mounted on the interior bottom wall of the cavity.