This paper presents a novel approach of customer-oriented design for translating customer's perception into product design elements. The mapping relation between form elements and customer's Kansei is performed by the Grey System Theory and Linear Regression Model. The established mathematic mapping model is used as the prediction core to construct a design expert system. Through the help of the developed product form design expert system, users can easily catch the prototype of customer-preferred product form for a specific desired image. Further, this developed expert system provides a direct linkage to 3D drawing software and related data base; users may modify or add their creative thinking to the prototype to create popular merchandise.