The paper presents an analysis of the continuous outgoing longwave radiation (OLR) based on time and space by using the wavelet-based data mining techniques. The analyzed results reveal that the anomalous variations exist prior to the earthquakes. The methods studied in this work include wavelet transformations and spatial/temporal continuity analysis of wavelet maxima. These methods have been applied to detect singularities from OLR data that correspond to seismic precursors, particularly to a comparative study of the two earthquakes of Wenchuan and Pure recently occurred in China.