A method of absolutely radiometric calibration of FY-2C infrared split-window channels using sea buoy data and NCEP reanalysis data was introduced. In 2006, ten times remote sensing data were selected to obtain the radiometric calibration coefficients. The calibration results obtained from this new method were compared with the product brightness temperature look up tables. The results show that the biggest differences between the top of atmosphere (TOA) brightness temperatures inversed from these two suits of calibration coefficients were mainly located on low surface temperature pixels, such as top of clouds and snow covered areas and in normal temperature pixels like land and sea surface areas, the differences were mainly around 2K. This new vicarious calibration method can increase the calibration frequency and provide a methodological foundation for the Real-time radiometric calibration of FY-2C infrared split-window channels.