The invention discloses a bridge girder erection machine protective guard, belonging to the technical field of hoisting equipment. The bridge girder erection machine protective guard comprises a rectangular fence composed of two lateral guardrails and a longitudinal guardrail; the two lateral guardrails are centrosymmetric, and the connection part thereof is provided with a lock catch; the lateral guardrail is connected with the longitudinal guardrail in a rotary manner; a steering draw bar is arranged between the included angle of the two guardrails; the longitudinal guardrail is provided with a trapezoid frame extending upwards; the longitudinal guardrail is connected with the trapezoid frame by a connecting rod; the front part and the rear part of the tail end of the trapezoid frame are respectively provided with a front flange and a rear flange; a rear supporting foot protective frame is arranged at the front part of the tail end of the trapezoid frame. The ridge girder erection machine protective guard of the invention has low cost, simple manufacture and convenient dismounting, saves storage space, is convenient for transportation, and can give full play of the advantages of the mechanized operation of cranes, thus greatly improving the operating efficiency, lightening the labor intensity of workers, and being suitable for erecting use of various simply supported beams.