Abstract: To meet the demand for compactness in long-wave infrared zoom optical systems, a linear dual-group linkage continuous zoom structure was utilized to simplify the system design. A compact long-wave infrared zoom optical system was developed using an uncooled infrared detector with a 384×288 array and a 25 μm pixel size, incorporating four single-crystal silicon (Si) lenses. The system has a total length of 160 mm, operates in the 8-12 μm wavelength band, offers a zoom range of 100-200 mm, a field of view from 3.42° to 6.80°, and maintains a constant F-number of 1.4. The design incorporates a diffractive optical element to achieve athermalization and eliminate secondary spectrum aberrations. Additionally, a conical surface and an even-order aspherical surface are introduced to balance spherical and chromatic aberrations caused by the long focal length and large aperture. The design results indicate that the system is compact and can achieve high-quality infrared thermal imaging within a temperature range of -40℃ to 60℃. The modulation transfer function (MTF) across the entire field of view exceeds 0.3 at the Nyquist frequency of 20 lp/mm. The zoom cam curve is smooth and free of inflection points, and the tolerance analysis confirms good manufacturability.