Abstract: The stator cooling water system undertakes the crucial task of cooling the stator winding of the generator, and the qualification of its water quality is of vital importance for the safe and reliable operation of the generator. This paper briefly describes the principle of the stator grounding protection of the generator and the configuration of the unit protection setting values, and elaborates on the process of handling this accident. After the abnormal increase in the conductivity of the stator cooling water triggered the stator grounding protection fault alarm, the professionals immediately carried out fault analysis, investigation and treatment, restored the normal water quality of the stator cooling water in the shortest possible time, eliminated the stator grounding fault alarm in a timely manner, and took effective preventive measures after the accident to ensure the safe and stable operation of the generator set.