Considering the non-portability and low efficiency of the measurement of bidirectional reflectance distribution function at present, a measurement system of bidirectional reflectance distribution function based on multi-rotor UAV was developed. The system is mainly composed of multi-rotor UAV and visible - short wave infrared spectrometer, with the observation lens of the spectrometer controlled by a high-precision UAV cradle head. The spectrometer adopts two wave band detection units, and the overall spectral coverage is 400～1700 nm. The two detection units of the spectrometer detect signals with flat field concave grating and linear array detector, and their spectral resolution is better than 3nm and 12nm respectively. In order to verify the comprehensive performance of the measurement system of bidirectional reflectance distribution function based on multi-rotor UAV, the surface directional characteristics of Dunhuang radiation correction field were measured using the measurement system. The experimental results show that the portable measurement system can greatly improve the measurement efficiency of bidirectional reflectance distribution function and provide a useful reference for the future development of measurement of bidirectional reflectance distribution function.