In order to ensure the accuracy of aerosol optical characteristics observation in onorbit automatic calibration of satellites, field calibration techniques of sunphotometer in Dunhuang test site were studied, including Langley calibration based on relatively stable atmospheric conditions and cross calibration based on high precision reference instruments. The calibration results show that the maximum deviations of aerosol optical depth inversion from high precision sunphotometer compared with CE318 sunphotometer are within 0.015 and 0.01 respectively by Langley method and crosscalibration method. The effects of atmospheric conditions and instrument parameters on field calibration were calculated and analyzed. The calibrated high precision sunphotometer and CE318 sunphotometer were placed in Qinghai Lake for synchronous comparison observation. The maximum deviation of aerosol optical depth is within 0.01. The influence of field calibration error of sunphotometer in Dunhuang test site on onorbit calibration of satellite is less than 0.21%, which shows that the calibration results can meet the accuracy requirements of satellite onorbit automatic calibration.