The invention relates to a tunnel collapse life saving machine. The tunnel collapse life saving machine comprises a diameter-varying cutting head, a screw conveying shaft, a screw conveying shaft rotation drive device, a life-saving barrel, a propulsion system, a hydraulic pump station, a base plate, a power distribution cabinet and a control cabinet, wherein the screw conveying shaft is sleeved in the life-saving barrel. According to the life saving machine, the diameter-varying cutting head is used for cutting collapsed soil bodies in a manner of breaking rock; the excavation diameter can be timely adjusted in the propulsion process; cut muck is discharged form the rear end of the life-saving barrel through the screw conveying shaft; the life-saving barrel is propelled along with the propulsion of the screw conveying shaft; when the screw conveying shaft is drawn out, the life-saving barrel forms a safe passage, so that personnel trapped by collapse in the tunneling process can be quickly and safely rescued in a human-friendly manner; meanwhile, the screw conveying shaft and the life-saving barrel in the life saving machine consist of a plurality of sections, are lengthened in a manner of changing steps and facilitate long distance excavation; and a steel wire rope is used for tensioning the front end of the screw conveying shaft, so that the downwarping of the screw conveying shaft is reduced, and the normal work is ensured.