Abstract: In response to the corrosion defects and other issues on the steel cladding of the spent fuel pool in nuclear power plants, this article adopted the repair method of local dry underwater TIG welding to repair the cladding.Firstly, the designed pressure environment simulation system was used to conduct dry welding tests within a pressure range of 0.3MPa, and obtain the optimal welding process for the cladding under different pressures. Based on the optimal process parameters in a dry environment, an exploration of local dry underwater welding process was carried out, and metallographic testing was conducted on the cut samples of the welded joints. The macroscopic crystal phase results showed that the weld formed well without cracks or pores, and the results of microscopic crystal phase testing indicated that the microstructure matrix was dendritic austenite, with ferrite between dendrites, no fiber cracks or precipitates were found. This paper lays the foundation for the in-service repair of the spent fuel pool cladding in nuclear power plants.