Abstract: Based on the theory of matrix optics, the first-order properties of the zoom system of the three-element variable focal power devices were analyzed, and the control equation of the focal power based on the system magnification was obtained. Combined with the initial parameters of the three-element system and taking the minimum spherical aberration as the objective, the initial structure of the system was designed, the control function of the shape parameters of the lens was obtained, and the focal power and image quality were evaluated and calculated. Finally, the design example was compared and verified. The results show that the solution of the optimal value of the minimum spherical aberration is reliable. The starting point and method of the design provide a theoretical research reference for the further design of zoom system by using variable focal power devices.