The energy consumed by mechanical products is huge, and its using ratio is low. In view of these problems, several key technologies of product energy-saving design were discussed. Based on the life cycle theory, the information model of product energy-consuming was established. Subsequently, the processing model of energy gene was analyzed through the n-m mapping. The processing model was set up by using the method of IFED3 and the energy gene distilling strategy was put forward. Finally, the optimization of energy-saving design method and the possible feedback mechanisms were discussed respectively.