Abstract: Following the trend of miniaturization and large fields-of-view for infrared lenses, we designed a large-field-of-view athermalized compact long-wave infrared lens using ZEMAX. The system matches a 384×288@17 μm uncooled long-wave infrared detector with an operating band of 8 μm to 12 μm. The F-number of the system is 1.6. The designed system has a larger field-of-view than a traditional infrared lens, with a full field-of-view reaching 72°. The size of the designed system is small with a total length of only 6.96 mm. The primary lens system lens uses only 3 lenses. Aberration correction and athermalization was realized by combining two infrared materials and six aspherical surfaces. The system has a working temperature range of −40℃ to 60℃. Simulation results show that the MTF of the full field-of-view reaches 0.5 at a spatial frequency of 15 lp/mm and 0.15 at a spatial frequency of 30 lp/mm. Further, to increase the filling factor of the infrared detector and improve energy efficiency, a microlens array is placed in front of the infrared sensor. Miniaturization of the infrared optical system was achieved, providing a solution for the application of thermal imaging cameras on smartphones.