A metal melting apparatus has a heating furnace, a melting furnace mounted on the heating furnace, a high-cycle regenerative system (HRS), a raw material feeding device and a melted material feeding device mounted on the melting furnace. The HRS heats and recycles high temperature air in the heating furnace and guides the high temperature air to the preheating screw to preheat metal materials in the preheating screw. Thus, a time for melting the metal materials from solid to liquid is greatly shortened. Furthermore, a series of processes for preheating the metal materials in the raw material feeding device, melting the metal materials in the melting furnace and injecting the molten materials to the molds is fluent, time-saving and safe, and can progress continuously.