Abstract: This paper reviews the mainstream technologies used in current CAD systems, including feature-based modeling, history-based modeling, parametric technology, and component technology. Research issues in current CAD systems, such as CAD and Internet, advanced surface modeling, data exchange, 2D vs. 3D CAD, and support for conceptual design are discussed. The paper concludes with some predictions on future CAD systems, with focuses on computing environments, mechanical CAD, data exchange and sharing, and part modeling technologies.