The spectral emissivity and temperature of the Dunhuang site, China, are important parameters for on-orbit radiometric calibration in thermal infrared band of satellite remote sensor based on the Dunhuang radiometric calibration test-site. In August 2018, the surface spectral emissivity of Dunhuang radiometric calibration test-site were measured repeatedly under different time and observation conditions using a portable Fourier transform infrared spectrometer (D&P 102F) and an infrared standard plate. Based on the iterative spectrally smooth temperature and emissivity separation algorithm (ISSTES), the spectral emissivity and temperature of Dunhuang site are separated by setting the temperature difference interval with different precisions and performing multiple iterative smoothing analysis on the measured field spectral data. Compared with the emissivity of CE312 channel obtained by multi-channel temperature and emissivity separation algorithm, the results show that the deviation of emissivity of each channel is within 0.011, which verifies the spectral emissivity and temperature of Dunhuang site obtained in this work have better accuracy. This experiment provides a reference for the on-orbit radiation calibration of satellite remote sensors based on the Dunhuang calibration field.