Abstract: This paper focuses on the oil leakage problem of the iron core and clamping part grounding bushing of a 500kV transformer in a pumped storage power station. Through in-depth analysis and research on the on-site operation, maintenance, and structure of the grounding bushing, the causes of oil leakage from the grounding bushing were identified. Combined with the internal inspection of the transformer after oil drainage, the oil leakage problem of the transformer grounding bushing was eliminated.To prevent on-site construction personnel from damaging the iron core clamping part grounding bushing due to collision, it is suggested that for transformers with a structure where the iron core clamping part is grounded through a porcelain bushing, a protective cover should be installed on the upper part of the grounding bushing.After multiple unsuccessful attempts to handle the oil leakage of the iron core clamping part bushing, the cause should not be simply attributed to loose bolts or aging seals; instead, the problem should be analyzed from multiple aspects and dimensions. This paper firstly studies and analyzes the structure of the grounding bushing, and conducts a stress analysis of the grounding bushing. Measures such as straightening the conductive rod, replacing the grounding bushing with a new one, and replacing the sealing ring with a new one were adopted, ultimately solving the oil leakage problem of the iron core clamping part grounding bushing.This paper provides a reference for the analysis and handling of similar problems in the future.