The invention discloses an auxiliary travel device for a bridge girder erection machine, which comprises a support, a bracket, two pins, a plurality of travel wheels and a motor, wherein the support consists of two cross beams, two lower upright posts, four inclined struts and a plurality of lower connecting systems; the bracket consists of two upper upright posts, two travel wheel grooves and anupper connecting system; the pins are used for mutually connecting the support and the bracket; the travel wheels are arranged in the travel wheel grooves; and the motor is arranged outside the travel wheel grooves, and the output shaft of the motor is connected with the travel wheels through gears. The auxiliary travel device for the bridge girder erection machine can complete the travel of the bridge girder erection machine under the cooperation of a middle leg travel device on the bridge girder erection machine by 2 to 3 constructors; and because girder transporting rails are not needed tobe laid as in the prior art, the labor intensity of the constructors and required manpower can be reduced, the construction period can be greatly shortened, the work efficiency is improved, and the construction cost can be greatly reduced.