Abstract: Super duplex stainless steel (SDSS) is widely used in marine engineering, petrochemical and other fields due to its excellent mechanical properties and corrosion resistance. This paper systematically studies the KD-TIG (Keyhole Tungsten Inert Gas) deep penetration welding technology of SDSS super duplex steel, and analyzes the influence of welding process parameters on weld formation, microstructure evolution and performance. The research shows that the KD-TIG welding technology can achieve single-sided welding and double-sided formation of 5mm large root V-shaped groove SDSS super duplex steel, and the welding efficiency is 5-10 times higher than that of traditional TIG welding. By optimizing the heat input and controlling the ratio, the weld microstructure with balanced ferrite-austenite two phases can be obtained, and its physical and chemical properties meet the design requirements. The research results have important guiding significance for promoting the application of KD-TIG welding technology of SDSS.