Long-wave radiation which escapes from Earth-atmosphere system often obviously changes before the occurrence of major natural hazards, therefore the research of OLR is necessary for the short-term forecast and early warning of disasters. This paper analyzed the long-wave radiation background field of Chinese mainland by using outgoing long-wave radiation (OIR) data from National Oceanic and Atmospheric Administration (NOAA), USA. The results showed that: the OLR value changed more obviously with the variation of latitude than that with longitude, and there are strongly seasonal and regional variations in outgoing long-wave radiation.