Abstract:In this paper,the author presents a technique for estimating OLR from FY3A IRAS multichannel radiance observations. It includes the development of an OLR inverse model by infrared radiative transfer calculation and regression analysis ,and the incorporation of the model into the IRAS OLR processing software. The RMS of the model for global 3812 soundings is 353 W/m2,which shows a much higher quality of IRAS model than that of NOAA AVHRR. The author gives an example of FY3A IRAS global OLR product,and carefully compares IRAS OLR product with that of NOAA-17 AVHRR OLRAnd the following conclusion is obtained: from FY3A IRAS radiance observations OLR product of high quality can be produced which is better than the OLR of NOAA AVHRR.