Continuous zoom optical system has extensive and essential practical applications in the field, such as law enforcement and evidence collection, forest fire, maritime search rescue, road traffic, unmanned aerial vehicle reconnaissance. In order to improve the zoom system performance index, and realize the miniaturization of system, the focal length of 2.68 mm to 17.5 mm, 4.7°-31° field zoom system is designed by using the Zemax optical design software and optimization calculation. The whole system is composed of four groups of ten pieces of lens. The F number is 2.15-3. The MTF curve at 250 lp/mm is greater than 0.25. Distortion is within 4.5%. The optical length is less than 27 mm. Total mass is less than 0.77 g. The system has a compact structure, light weight, high resolution, excellent image quality, etc, which is a miniaturization of microminiature continuous zoom.