Abstract: The zoom optical system is not only suitable for daily life such as photography, surveillance and microscopy, but also widely used in aerospace and national defense construction. With the expansion of the application range, there are more and more requirements for its performance indicators. A 15 mm~300 mm wide-spectrum four-component continuous zoom optical system was designed, which used a positive group compensation structure to achieve 20 times optical zoom, operating in the spectrum range of 450 nm~900 nm, and the working temperature range was −40 ℃~ 60 ℃. It also used 18 pieces of spherical glass lenses with a total length of 160 mm, a maximum aperture of 66 mm, and a long focal F number better than 5, which showed the system had compact structure and met the miniaturization requirements. In the visible light band, the modulation transfer function (MTF) of the central field of view was greater than 0.4@145 lp/mm, and the MTF of full field of view was greater than 0.2@145 lp/mm. In the near infrared band, the MTF of the central field of view was greater than 0.45@60 lp/mm and the MTF of full field of view was greater than 0.2@60 lp/mm. From the design results, the proposed design meets the requirements of high performance index, and has certain reference significance for the design of zoom optical system with wide spectrum, large zoom ratio and miniaturization.