An introduction is made to the principles, functions and dataprocessing procedures of the newly developed polarorbiting meteorological satellite realtime monitoring system of forest fires. This system can process the data of forest fires while a satellite is passing by. It has solved the problem of realtime monitoring that many other meteorological satellitemonitoring systems cannot handle. The realtime monitoring system is a parallel processing system composed of three computers. It divides the time sequence of recognizing a fire site from obscurity to confirmation into three steps, and the time sequences of datareceiving, firesite judging, firesite targeting, and displaying are distributed in three computers, which operate synchronously. This system has been put to operational use in the Guangzhou Meteorological Satellite Ground Station since 2005. Compared with the former satellite remote sensing monitoring system, it can monitor and report forest fires 30 minutes earlier.