For continuous zoom lens, the optimal design of pressure angle of cam curve is an important factor influencing the function of the lens.Based on the cam driving structure and mechanics theory, an analysis is made to the influence of the cam curves pressure angle on the transmission torque.With consideration of the machining error and pressure angle model, the constraint conditions and optimizing principle are proposed.By using the smooth characteristic of Gauss function, the optimization method of non-uniform widening of the cam curve is realized along vertical direction of the optical axis, and the maximum pressure angle of the cam curve is restrained.The method has been applied for optimization of a cam curve of a zoom lens obtained by optical design, for which the range of pressure angle is optimized from 0°~39.01° to 15°~31.16° under constraints, and the maximum pressure angle is reduced by 20.12%.These results indicate that the method can be effectively applied to the design of cam zoom system for improving the performance of the system.