Abstract: Based on the infrared scanning image system theory, a continuous zoom area array scanning infrared optical system using 1 280×1 024 pixel@12 μm/F2 large area array medium-wave refrigeration sensor was designed. According to the requirements of the design technical indicators, the optical application parameters were analyzed, and then it was determined that the image scanning method was used to compensate the surface movement in the integral time generated by the movement of the scanning platform, so as to solve the thermal imaging tailing phenomenon during the scanning of the area array detector. The telescopic system adopted the structure forms of secondary imaging, negative component magnification and positive component compensation to realize continuous zoom, that was, the structure of the optical system was determined as the type of thrice-imaging. It was also necessary to make analytical adjustments to the cam curve and the hot/cold reflections of the scanning optical system in the design program. The optical simulation results show that the MTF value of the full field of view at the frequency of 42 lp/mm is greater than 0.3 under the condition of scanning galvanometer round trip, the cam curve is smooth without inflection point during the whole zoom process, and the maximum pressure angle is less than 50°. Finally, the imaging experiment test of the system was carried out. The test results show that the control system can complete the continuous zoom in the area of 60 mm to 600 mm, the scenery around the object is clearly visible in the zoom stage, and there is no cold reflection. At the same time, the imaging of the system without tailing phenomenon is clear and stable during the rotation scanning process. The system can be used in infrared systems that integrate continuous zoom search and tracking.