Abstract: Earthquakes often cause a great impact on or even do harm to buildings, equipment, and facilities. It is necessary to strengthen the detection and analysis of earthquake impacts on the operation safety of hydro-generator units. This paper focuses on the earthquakes of intensity above M5.0 that occurred in southwest China in recent years and describes their impacts on the operation safety through monitoring and analyzing the stability parameters of large hydro-generator units owned by China Three Gorges Corporation. Meanwhile, by the finite element analysis results of the electromechanical equipment at modern hydropower stations, we conclude that operation safety of hydro-generator units that have adopted aseismic design will not be affected when suffering from earthquakes below the basic seismic intensity.