Since the Xingtai earthquake in 1966,the geo-electrical resistivity observation has been implemented in a large scale in China.At present,approximately 90 geo-electrical resistivity sta-tions are in operation in mainland China as a result of network construction in the period from the seventh five-year plan to the tenth five-year plan.In the long-term observation,significant anoma-lies in geo-electrical resistivity have been recorded before the MS 7.8 Tangshan earthquake in 1976,the MS 7.2 Songpan-Pingwu earthquake in 1976,the MS 7.6/7.2 Lancang-Gengma earth-quakes in 1976,and the MS 8.0 Wenchuan earthquake in 2008.Moreover,several moderate-strong earthquakes have been accurately forecasted on the basis of geo-electrical resistivity observation. However,many people still have different understandings on the anomalies in geo-electrical resis-tivity before earthquakes due to lack of knowledge of earthquake preparation and occurrence processes,crustal structure,and medium conditions from the epicentral area to observation station and dynamical processes of underground media.Such confusion may be attributed to the small de-tecting depth/range of current DC geo-electrical resistivity stations and the complicated behaviors of anomalies in geo-electrical resistivity that include the anomalous changes caused by observa-tional environments.The Baochang geo-electrical resistivity station in Inner Mongolia has continu-ally observed for more than 30 years and has met the technical requirement of geo-electrical resis-tivity observation in China.Many moderate and great earthquakes have occurred near this sta-tion.This study evaluates the reliability of long-term geo-electrical resistivity observation data of the station by processing the data recorded since 1985 by using the normalized variation rate method and the Fourier sliding method for identifying earthquake-related anomalies in geo-electri-cal resistivity and studies the monitoring ability in the medium-term and imminent stages before an earthquake occurs.The research results are as follows:Baochang station has not been affected by the observational environment in the long-term.Its observation data are valuable in earth-quake scientific research and earthquake prediction,and the anomalies identified by the aforemen-tioned two methods are credible.We believe that the geo-electrical resistivity observation of sta-tion Baochang has certain monitoring ability for moderate-great earthquakes near the station.The geo-electrical resistivity of two orthogonal channels of the station has shown continuous medium-term and short-term anomalies around the station related to the earthquakes.Furthermore,the de-creasing or increasing anomalies which lasted for one year,were also recorded before the long-dis-tance MS 8.0 or above earthquakes that occurred near mainland China and its surrounding area, which were historically well corresponded to the occurrence of the great earthquakes.%分析了内蒙古宝昌台地电阻率长期观测数据的可靠性，应用归一化变化速率方法和傅氏滑动方法处理了1985年以来的地电阻率观测数据，研究了该台在地震前中期、短期阶段的监测效能，结果显示：该台两个正交测道的地电阻率观测对台站周围的中等以上地震有一定的监测能力，表现出了与地震有关的震前持续性的中期、短期异常，且在中国大陆及周边发生的数次远距离8级以上大震前也记录到持续1年尺度时间的下降/上升异常。
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