In this study, we analyzed observation data recorded prior to the occurrence of an M5.2 earthquake in Cangshan county, Shandong province, which were recorded by eight deep-well geoelectric stations within a 100 km radius of the epicenter. The results reveal varying degrees of anomalies at all stations. Further analysis of these anomalies indicates that the anomalies appeared synchronously 26 months prior to the earthquake at three stations located at the cross section of the Yishu and Cangni faults; 16 months prior to the earthquake at two stations located between the two faults; and 13 months prior to the earthquake at two stations located several faults away from the epicenter. Our analysis of the anomaly features shows that their times of appearance and changes are related to the epicentral distance, tectonic position of the station, tectonic setting, and the direction of the principal compressional stress of the regional stress field. The research suggests that observations of deep-well geoelectricity networks are extracted directly from the internal bedrock and are significant for earthquake monitoring and prediction.