Abstract: In order to improve the temperature stability of long focal length zoom lens, the influence of temperature on the optical system was analyzed. By the simulation analysis of long zoom lens optical system for temperature in CODE V, it is found that the temperature has a great effect on the image quality of optical system. At first the initiative focusing compensation mode was adopted to compensate the temperature effect of the optical system. Although the image quality improved after compensation, the CCDs max frequency of modulation transfer function (MTF) is low, and the best image plane of every focal length of zoom system cannot parfocalize. By adopting the mechanical passive compensation and active focusing compensation to get the compensation of temperature, the optical system can realize good image quality within the required full temperature range, and the MTF is greater than 0.5 in short focus while greater than 0.25 in long focus. The focus length can be compensated, and the best image plane of each focal length can parfocalize and overlap with the CCD image plane.