In order to adapt to safety and quality inspection requirements of different types of constructions based on the infrared non-contact method, a large zoom-ratio uncooled infrared continuous zoom imaging optical system with a focal length of 30～180 mm is designed based on a new type of high-performance uncooled longwave infrared detector whose resolution is 1024×768，and pixel size is 14 μm×14 μm. The system uses positive group compensation structure whose variable times group focal degree is negative and compensation group focal degree is positive, and distributes the focal degree of each lens group reasonably as well. Its operating band is 8--12 μm, and F number is 1.2.The imaging effect of the system is analyzed, and the results show that the system has a good image quality in the zoom process, and the MTF value at the detector characteristic frequency 36 1p/mm is greater than 0.3, which meets the application requirements.