Abstract: By using the radio sonde data and Lowtran 7, the radiance is calculated, and the calibration coefficients of FY-2 and GMS-5 water vapor channels are fitted. During the period of around equinox eclipse, the temperature on satellite would change rapidly, and the vicarious calibration combining with in-flight calibration would be considered. The validations are made using radiosonde data and GMS-5 observational values. The vicarious calibration has got a good result in the operations for half a year.