A light and compact imaging spectrometer (LCIS) optical system suitable for unmanned aerial vehicles (UAV) is designed in this work. The operating wavelength of the optical system covers400?1000 nm, with an F number of 3.3, a field of view of 11o, and a spectral resolution better than 3 nm. The optical system is simulated and optimized using Zemax software. The optimization results show that the maximum root mean square (RMS) radius of the dot plot for this system is 4.221 μm, which is less than half of the size of a single pixel, the maximum values of smile and keystone are 1.30 μm and 1.16 μm respectively, accounting for 8.69% and 7.73% of a single pixel size, and the modulation transfer function (MTF) value at 33 lp/mm is better than 0.7. All evaluation results show that the optical system has good imaging quality. In addition, the optical system has a volume of 190 mm × 160 mm × 90 mm, indicating that the system not only has high spectral resolution and good imaging quality, but also has the advantages of small size and compact structure. This research provides core technical support for the development of light and compact imaging spectrometer, and also lays a foundation for in-orbit radiometric calibration of remote sensors based on UAV borne imaging spectrometer.