Considering that the space and weight of unmanned airborne equipment is limited, an unmanned airborne high spectral imaging optical system on the basis of liquid-crystal tunable filter liquid crystal tunable filter, which has 46 channels. The working spectrum of the system covers the visible light to near-infrared light (0.45 ~0.9 μm), the spectrum resolution is 10 nm, the focal length is 81.25 mm, relative aperture is 1/2.5, the full viewing field angle is 12°, the maximum distortion is less than 0.12%, the ground pixel resolution is 0.4 m, the ground breadth is 1 km×0.87 km with 5000m of flight level. The liquid crystal tunable filter overall embedded design is adopted and the aberration produced by liquid crystal tunable filter is revised. The imaging quality of the system is excellent under the no vignetting design condition, the root-mean -square diameter of maximum dispersed spot is less than 5 μm, the modulation transfer function of every viewing field is more than 0.54 under the sCMOS Nyquist frequency situation. Zemax multi-configuration and thermal analysis were used to simulate the imaging quality of system. 25℃±5℃ of system temperature control scheme and 35℃±1℃ of liquid crystal tunable filter temperature control scheme was confirmed. In the range of 3 km~6 km aviation altitude, the system doesn′t need image motion compensation.