Abstract: Presents a design method that ensures the ingenuity in the product form while maintaining the integrity and exact expression of user's needs.The key idea is to establish an automatic design system that can transform the user's needs in language form into the features of products real-time.A rifle was taken as a asample of study and students who have received formal drills in the army were chosen as simulant clients in this study.The theory of fuzzy set and semantic difference was adopted to evaluate the relationship between user's needs and product features as well as their alternatives.Fuzzy analytic hierarchy processing was utilized to judge user's satisfaction.The method can also be applied to other product form designs.