Small box girder transporting and hoisting method

The invention discloses a small box girder transporting and hoisting method which comprises the following steps: moving a rear support to a position 20-30m away from a rear support leg, moving two lifting trolleys to the top of the rear support to serve as a counterweight, moving a middle support leg to a position 1-2m away from a girder end and anchoring, retracting the rear support leg, enabling a rear support wheel to fall onto a support pad, enabling the middle support leg to be stressed on the lower surface of a sleeper beam of a front support leg, and enabling the middle support leg to be stressed on the lower surface of the sleeper beam of the front support leg. The front supporting leg is lowered to be jacked up and stressed by utilizing a reverse riding wheel mechanism on the middle supporting leg and a power mechanism of a rear riding wheel walking wheel box, and the front supporting leg is fixed, the rear supporting leg is jacked up and stressed after a main beam of the bridge girder erection machi