The utility model discloses a metro rail layer which comprises a running mechanism, four supporting legs, a lifting device, a hoisting mechanism, a main beam mechanism, a cable drum, an operating system, four lifting hydraulic cylinders, two telescopic hydraulic cylinders and a hydraulic control system. The lifting device comprises two lifting frames, and each lifting frame comprises two lifting sleeve pipes, an upper cross beam and a lower cross beam; the main beam mechanism comprises a middle beam, and the two ends of the middle beam are respectively provided with a telescopic beam; each running beam is provided with two supporting legs and two lifting hydraulic cylinders; the bottom ends of the supporting legs are fixedly connected with the running beams, and the top ends of the supporting legs are connected with the bottom ends of inner sleeve pipes; the bottom ends of the lifting hydraulic cylinders are fixedly connected with the running beams, and piston rod ends of the lifting hydraulic cylinders are connected with lower cross beam pin shafts; the other end of each telescopic beam is connected with the corresponding upper cross beam through a flange disc, and cylinder sleeves of the two telescopic hydraulic cylinders are fixed on the top of the middle beam; the piston rod end of each telescopic hydraulic cylinder is connected with one telescopic beam through a pin shaft.