This paper analyzes the current status and inadequate of three-dimensional parametric design, and introduces the conceptions and principles of KBE (Knowledge Based Engineering) technology and the parametric design. The key techniques of parametric design system are studied based on the platform of combination of SolidWorks as three-dimensional feature modeling software, Microsoft Access as supported database and Microsoft Visual Basic as the development tool. Firstly, we divide the product into modules by functions. Secondly, invoke corresponding knowledge and methods of design and calculation in the KBE knowledge base to perform design and calculation. Then we use parametric modification method combined with equations, values link and design tables to get the parametric models, judge the rationality of the design parameters through finite element analysis, and create the drawings which meet the processing and production requirements using drawings automatically adjustment technology. Finally a case study of stacker design is given to validate these techniques of parametric design system, and show that the techniques have great significance for improving product design quality, shorting the design cycle and improving the competitiveness of enterprises.