There are some anomalies before the earthquake, especially the large earthquake. However, such abnormal information is too difficult to identify. Therefore, we cannot make full use of the abnormal information to predict the occurrence time of the earthquake in order to reduce the impact of the earthquake. To solve this problem, an anomaly mining method before earthquake based on the quantum walk algorithm is proposed to extract seismic Outgoing Long-wave Radiation (OLR) anomalies before the Wenchuan earthquake and the Lushan earthquake. Then, calculate the P value, anomaly value CD before and after the earthquake. Through statistical analysis method, the relationship between OLR anomalies and earthquake is explored. What is more, the algorithm is extended to the 8.0 magnitude and above earthquakes in the nearly last ten years. Through experiments, the effectiveness of the algorithm is verified. The experimental results show that the algorithm can effectively reflect the anomalies before and after the earthquake, and the larger the earthquake is, the more obvious anomaly is. Therefore, this algorithm is suitable for pre-earthquake anomaly excavation.