The paper studies the observational data of earth resistivity in Linxia seismic station, Gansu, since 1981. To discuss the corresponding relation between the two direction findings, EW and NS, and the flow rate change of Daxia River, the variation characteristics of earth resistivity were analyzed by using mathematical statistics and correlation analysis methods. It can be concluded that there was a high correlation at the two direction findings, which was probably related to the electricity structure of underground media. In addition, analyzing the impact of precipitation and the static water level, we found that the influence of static level is remarkable. Besides, the data of earth resistivity is sensitive to the moderately strong earthquakes which occurred in the southwest of Gansu and the junction of Gansu and Qinghai. The abnormal annual descend is the main precursory anomaly information, which showed that there is a greater magnitude with a longer duration of abnormality. The anomalous change of the earth resistivity is remarkable in the moderately strong earthquake group of Gansu and Qinghai regions, indicating that the duration of abnormal was long, the amplitude of variation was large and the recovering time was slow.