Abstract: This paper introduces the structure, characteristics, and key technologies of a special CNC system for key machining. The system uses several numerical key codes to describe its trajectory parameters. This method embodies a programming technique with key-machined characteristics. Practice has proven that the system possesses high machining accuracy, efficiency, and automation. Keywords : key machining; numerical coding; CNC; special milling machine; open system architecture Currently, it's common for the same key to open other vehicles, and its processing precision affects the quality of unlocking. Currently, key processing relies mainly on manual adjustment to match machined keys, resulting in low precision and poor system flexibility. Since there are thousands of different types of keys, relying solely on manual adjustment and memorization often leads to errors and makes it difficult to avoid repetitive issues. Therefore, developing such specialized CNC milling machines is highly practical. The key processing CNC milling machine introduced here uses a 3-axis stepper motor drive and an industrial PC as the control system. Dual milling cutters can process keys from both sides, allowing for the processing of several keys at once to ensure uniformity and improve processing efficiency. Click here to download the original paper.