In 1999, Dunhuang remote sensing satellite radiation calibration station began regular operation. With Dunhuang urban construction and economic development, the radiometric field surrounding has changed. A great field measurement campaign was conducted in Dunhuang site in summer, 2013. The CIMEL sunphotometer was used to measure the optical characterization of atmosphere in Dunhuang, and a lot of data were obtained about atmospheric optics in loud clearing condition of four days. Data from aerosol-bands of sunphotometer were used in a Langley method to determine spectral optical depths of aerosol. The aerosol optical depth at 550 nm in Dunhuang is about 0.3. The results showed that the aerosol concentration of atmosphere in Dunhuang was small and suitable for in-flight calibration for remote sensing satellite sensors.