Abstract: After the submersible pump and conservator capsule of the main transformer reach their service life, they need to be replaced to meet the normal operation of the transformer. This paper summarizes the replacement methods and precautions for the submersible pump and conservator capsule of the 500 kV main transformer of a large hydropower station, providing a reference for other hydropower stations, transformer stations and other transformers to replace the submersible pump and conservator capsule.