To detect water seepage and ensure the safety of Pumped Storage Power Station (PSPS) facilities, we apply the electrical resistivity method to evaluate the leakage when the water level is on the rise. We check whether there is a leakage channel near the cavern group of the underground powerhouse. We conduct the field survey and integrate the results with regional geological data to determine the distribution of faults and large cracks. Granite intrusions generate a variation of high and low resistance phases, representing granite porphyry and tuff, respectively. The interface between the two lithologies is the location of the fault zone. In general, the apparent resistivity of two does not change much, indicating that the rock masses are relatively stable. The internal fractures of the rock masses are not developed, and there is no visible water content. However, from the location of the lithological contact interface, the rock mass is broken. Therefore, we recommend that before constructing the lower reservoir, anti-seepage treatment should be carried out.