Abstract: An approach to represent user-defined features is proposed and implemented in a 2D parametric sketching package GS-ZDDS. It provides a mechanism for information sharing between GS-ZDDS and user's professional design program. It makes the design process more efficient and enables the reusing of designed part. By using user-defined features, the amount of programming needed to build user's professional design system can be reduced significantly, moreover, the buildup system can be extended easily.