In order to solve the shortcoming of reflectance’s manual measurement in vicarious calibration, improve the calibration frequency and obtain substantial and continuous data, an automated sited observing radiometer was developed which has eight channels with bandwidth from 20 to 40 nm covering the spectral range from visible to near-infrared. Furthermore, the data transmission was realized through Beidou satellite. The radiometer can realize automatic observation and data transmission without man attending. The operating principle of the instrument, the design schema and the characteristics of each unit were presented in detail, following the method and result of laboratory radiation calibration. The experiment of radiometer on Dunhuang testsite was been introduced at last.