In the design of continuous zoom optical system with mechanical compensation, in order to make the zoom system image continuously and smoothly, this paper proposes a method to reduce the cam curve pressure angle of the zoom system. By changing the equation of the zoom curve and applying the principle of dynamic optics, the pressure angle of the fitted compensation curve has a significant decreasing trend. In the original design, the pressure of the zoom curve is 31.4°, and the maximum pressure angle of the compensation curve is greater than 50°. Using the interpolation method to change the equation of the variable magnification group to obtain a new cam curve,the maximum pressure angle of the zoom curve is less than 37° and the maximum pressure angle of the compensation curve is less than 23°. A new cam curve is obtained that satisfies the requirement that the curve pressure angle is less than 45°.The results of the actual optical system test prove the feasibility of this method. By this method, the pressure angle of the cam curve can be reduced, the actual zoom system can image continuously and clearly.