Aiming at slow response speed and low accuracy of traditional continuous zoom lens control system, the design method of continuous zoom lens and its control system was improved. Magnifier compensation displacement curve was found using mechanical compensation theory. Based on control techniques of digital signal processing (DSP) and stepping motor, a control system was designed including DSP, stepping motor, stepping motor driver, keyboard control, computer communication and LCD block. Meanwhile self-locking blocks were added to promote safety and reliability of the control system. The experimental results show that the control system accuracy is within 0.01 mm and achieves the technical requirement of 0.12 mm.