Based on a 640×512 uncooled detector with a pixel size of 12 μm×12 μm, a high performance long wave infrared continuous zoom system is designed by the continuous zoom optical system design theory, with a focal length of 30~180 mm and a telephoto end F number of 1.2. Infrared materials such as germanium and zinc selenide are used in the system, and the off-axis aberration of the system is corrected by aspheric surface. The image quality of the system is evaluated from the aspects of modulation transfer function (MTF), spot diagram, distortion, etc. After the cam curve is optimized, the pressure rise angle of the zoom group in the short focal length is reduced, and the zooming process is smooth. Experimental results show that the system has the advantages of good imaging quality, smooth cam curve and compact structure, which is suitable for infrared monitoring field.