This paper introduces the principle

design method and main characteristics of class-based interior design CAD system. How to use ObjectARX to derive the classes a base class is discussed. The system was developed based on AutoCAD R14. It involves interior design functions (door design

window design

wall design

roof design

stair design and so on) and a block-database navigator. It can work in conjunction with AutoCAD's native functions. AutoCAD programming environment provides an object-oriented C++application interface that enables developers to use

customize

and extend AutoCAD. We take advantage of AutoCAD' s open architecture and ObjectARX to customize the main object's structure and styles. The system can dynamically create versatile objects and change the objects to satisfy the needs of users.