Precise measurement of radiation calibration field surface reflectivity and the ratio between diffuse and total radiation are required when using the irradiance-based method to determine the satellite calibration coefficient of each band. From June to August in 2013, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, allying with other units, calibrated X satellite by using the irradiance-based method in Dunhuang Radiometric Calibration Test Site. ASD, SVC spectral radiometer were used and the surface reflectance was obtained by reference board reflectivity modify method during the measure process. The surface reflectance measurement and data processing method were elaborated, and the reflectance characteristics between 2013 and historical data were contrasted and analyzed. The results indicated that the surface reflectance of Dunhuang Radiometric Calibration Test Site maintained good stability both in space and time.