Analyzing the monthly departure image of the remote sensing infrared bright temperature (BT) of MODIS/ Terra satellite,we obtained the following results:Firstly,the remote sensing infrared bright temperature appeared significant anomalous increase in the very large area,up to more than 150,000 km2 in two years before Wenchuan M8.0 earthquake and in one year before Yushu M7.1 earthquake,and the occurrence time of earthquake was closer,the anomalous increase range of the BT was higher and the area of it was larger.Secondly,the anomalous increase area of BT before the Wenchuan M8.0 earthquake was larger than that of Yushu M7.1 earthquake,which may indicate that there was a certain correlation between the size of anomalous area and magnitude.The statistic of anomalous numbers in monthly departure image of BT showed that anomalous increase of BT of continuous three months in one year was considered as the background level,and the anomalous increase of BT of more than six months in one year,which had medium term indicating significance for the occurrence time of M ≥7.0 strong earthquake in BT increase area in 1 ~ 2 years.