The development of IEC 61508 and IEC 62061 has converted the safe problem of the system into a risk control problem. Therefore, how to achieve functional safety on CNC (Computerized Numerical Control) systems with evergrowing complexity has become an urgent problem to be solved in the research on functional safety of CNC systems. Componentized design is an effective way to solve the above problems. The CNC system implements functions through hardware and software cooperation. Because software and hardware are logically equivalent, in the CNC system, the completion of work by hardware can also be accomplished by software. This paper abstracts the software structure of the open CNC system, proposes the design and development of a safety related component based on functional safety, and verifies that it can meet the complex functional requirements of the CNC system in the actual production and meet the needs of the functional safety.