AbstractBased on the outgoing long‐wave radiation data of geostationary satellite and their variation characteristics, this paper proposes a method for extracting earthquake thermal infrared anomaly, namely, the relative variance rate of power spectrum estimation. The proposed method is applied to analyze OLR for the Wenchuan earthquake and other five Ms ≥ 6.5 earthquakes in Mainland China. The results indicate that the power spectrum amplitude of OLR increased to different degrees before the great earthquakes. The characteristic period and characteristic amplitude are short and small in moist (low altitude) areas respectively, while the period and amplitude are long and big in arid (high altitude) areas respectively. The characteristics of observed thermal infrared anomalies are easy to be recognized. The method is very effective for extracting useful information and can be used to the extraction and analysis of earthquake‐related information.