This study aims to build three mathematical models to describe the recyclable energy for three different types of power generating shoes (PG shoes). We built three different types of PG shoes models and simplified the mechanical resistance into two springs. The spring deformation velocities of seven subjects were analyzed by motion analysis system and the property of the power generator was also measured. Finally, three mathematical models were built by relating all the data using curve fitting program. The results showed three curves of electric power from three PG shoes were all single hump during stance phase of walk. Different type of shoes will affect the walking pattern of the subjects and further affect the power generating ability. The mathematical models could be applied to the further designs of PG shoes.