Abstract: The monthly standard deviation of outgoing longwave radiation(OLR) was obtained in terms of the data around 75癝-75癗 and 0?-360? in 1980-2001.The results show that the OLR variation over low-latitude area is one order larger than that over middle- and -high latitude area in terms of the zonal average in the year.The area where the OLR has obvious interannual variation about 15W/m2 is located at tropical middle eastern India Ocean,the western Pacific warm pool and middle eastern Pacific.The OLR interannual variation over the warm pool is the biggest one.The next to it is that one over the tropical middle eastern Pacific,and then the smallest one among the three is that over the tropical middle eastern India Ocean.The OLR interannual variation in summer,which is around 11W/m2,is smaller than that in winter,which is around 15W/m2.The OLR variation also has obvious seasonal abrupt change.The OLR abrupt changes occur in May and June,and in October.The area of the maximum OLR interannual change is confirmed.