Monthly departure curves of Outgoing Longwave Radiation (OLR) at the intersections of latitude and longitude in a range of 32°~40°N and 89°~105 °E from July,1989~Dec.,1996 are drawn.Analysing these curves,variation characteristics of OLR before strong earthquakes are studied.The results show anomalous variations with opposite direction or oscillation of the OLR curves appear 1~4 months before strong earthquake at the intersections around the epicenter.Anomalous intersections are distributed in the shape of the belt before some earthquakes.