Using seasonal land surface temperature in Beijing area from four scenes Landsat TM data during 2005 and 2006 and the land surface temperature retrieved from thermal infrared, thermal field distribution characteristic and its spatial difference of four seasons are analyzed. Then, surface heat island intensities and air heat island intensities are calculated by using LST and air temperature observed by weather stations, and their seasonality are analysed. The results show that relative to suburb area, the urban has evident heat island effect, and strong heat island effect in each season to the rural area.