Abstract: Because of the bad working conditions, large module and large size gears used in mining machinery, marine equipment and other fields are prone to wear and other defects. Aiming at the repair of such gears, a gear hobbing and laser cladding composite machine is designed. The machine tool realizes cladding movement by adding laser cladding head controlled by servo axis on one side of the worktable of YK31125 CNC hobbing machine. It adopts the way of adding annular air curtain nozzle outside the powder nozzle of laser cladding head to obtain annular protective air curtain around the powder beam to adapt to laser cladding in an open environment. The control principle of the machine tool and the simple and humanized man-machine interface are given. By using this machine tool, the gear repair and hobbing can be completed, the gear repair cycle can be shortened, and the repair cost can be reduced.