Vacuum carburizing gas quenching furnace is loaded into the vacuum furnace, vacuumed and heated to purify the furnace, and after reaching the carburizing temperature, hydrocarbons (such as propane, etc.) are introduced for carburizing, and after a certain period of time, the carburizing agent is cut off, then vacuumed or filled with nitrogen for diffusion, and the cycle of carburizing and diffusion is operated. By vacuum carburizing by pulse method, it can make blind holes and small holes to obtain uniform carburizing layer. Vacuum carburizing can realize high temperature and fast carburizing (1050℃), which can greatly shorten the carburizing time and improve the production efficiency. The carburizing layer of the workpiece in the same furnace is uniform, no internal oxidation in the carburizing layer, no fatigue source, which greatly improves the service life of the parts.