Abstract: Integrating intelligent systems and available traditional CAD systems to intellectualize CAD systems is a fast and efficient way to implement an intelligent CAD system. This paper introduces an intelligent CAD systems auxiliary tool called PROPS which has been designed and implemented. Since PROPS can not only compile user's intelligent systems(programs) into C codes, but also provides users abundant interface commands to debug intelligent systems and trace inference process, it's a practical intelligent CAD systems auxiliary tool.