Abstract: Telescope is important to measure atmosphere optical parameters by tracking star or beaconing to measure data in real time. Based on the moving characteristics of beaconing at different speeds, design of a continuous zoom measurement system for atmospheric coherence length was required. The designed focal length of the system was 3 m~6 m, the wavelength was 486 m~656 m, the charge coupled device (CCD) size was 11mm and the entrance pupil diameter was 300mm. By using optical design software, a catadioptric zoom telescope system was designed which consisted of a Cassegrain telescope and three-component mechanically compensated zoom system. The optical zoom system has high quality, simple structure, low cost and smooth cam curve, and all the pressure rise angles are no more than 45. It can output real-time zoom data of focus length and is suitable for measuring the atmosphere coherent length real-timely on the occasion of high and low speeds.