Abstract: This paper concentrates on how to achieve the mapping from functional principle solution to specific product form when the functional principle solution of designing product has been obtained. Based on a proposed assumption, firstly, an algorithm to capture the implied functional constraints is presented. Then the way on how to obtain functional constraint families is given by the determination of similarity of functional constraints between design cases. Finally, an example of an electro-pet design is given to illustrate the application process, as well as demonstrate the feasibility of the approach proposed.