The wear of half axle gear seats inside the differential mechanisms shells is a common failure form. And it can be batch remanufactured by the surfacing method. A remanufacturing machine for repairing the wear of differential mechanisms shells was designed by combining sub laser welding technology with surfacing method. The remanufacturing machine is mainly formed with the workpieces rotating mechanism, the welding torchs horizontal moving mechanism, the welding torchs vertical moving mechanism, the welding wires automatic feeding mechanism and the welding torchholding mechanism. To get the spiral surfacing layer, the workpiece keeps uniform circular motion, at the same time, the welding torch does radial uniform linear motion. This machine can repair the wear of differential mechanisms shells, so it can be used for the batch remanufacturing of differential mechanisms shells.