The invention discloses a single-girder low-level balanced cantilever assembling bridge erection machine, belongs to the technical field of prefabricated segmental balanced cantilever assembling bridge erection, and mainly aims to solve the problems of large dead weight and excessive height of a conventional ridge erection machine. The single-girder low-level balanced cantilever assembling bridge erection machine is mainly characterized by comprises a girder, a front lifting overhead crane, a rear lifting overhead crane, a front main supporting leg, a middle main supporting leg, a rear main supporting leg, a segmental suspension beam and a tension platform, wherein the girder adopts a single rectangular frame structure, an overhead crane track is arranged on the girder, and a stainless steel track is arranged at the lower chord of the girder; the structure of the front lifting overhead crane is the same as that of the rear lifting overhead crane, and the front lifting overhead crane and the rear lifting overhead crane separately comprise two independent winch systems and an overhead crane cross beam; and the overhead crane cross beams straddle on the overhead crane track of the girder, and the upper parts of the two independent winch systems are fixed to the two ends of the overhead crane cross beam. The single-girder low-level balanced cantilever assembling bridge erection machine disclosed by the invention has the characteristics of being simple in structure, easy to operate and simple and convenient in construction process, and is mainly used in a condition that in a permanent structural design, the acting force of the bridge erection machine on a permanent structure is required to be small, and the bridge erection machine can pass a limit height.