Abstract: Based on plasma enhanced chemical vapor deposition and hollow cathode discharge technology, DLC coatings are uniformly deposited on materials such as cast iron, stainless steel, aluminum alloy, as well as on the inner surfaces of different pipes such as straight pipes, bent pipes, and U-shaped pipes. Furthermore, combined with plasma immersion injection technology, DLCcoatings are uniformly deposited on the surfaces of irregular parts such as gears, bearings, piston rings, and cutting tools.