To meet the needs of open system and specific requirements of CNC platform, the component Software-Bus-Adapter model (SBA model) is presented. In this model, functional modules and application modules are encapsulated into components and integrated through software bus. The software bus is bridge between components communication. And the adapters accomplished hybrid components interface and data format transformation, which can be added to and removed from the system at runtime. Based on The SBA model is proven to be a solid base for CNC developing system with high efficiency, interoperability, scalability and openness. Development Practice has proved that SBA - based model of CNC system has more efficient and better interoperability and flexibility.