Objective To study the difference in the passivation and corrosion behavior of tungsten-arc inert gas (TIG) welded joints of 316L stainless steel in different concentrations of H2S solutions. Methods In 0. 05,0. 1,0. 2,0. 4,0. 8 g/ L H2S solutions, the passivation behavior and corrosion resistance of the base material and the welded zone in TIG joints were investigated by polarization curves, potential step, potentiostatic polarization, and electrochemical impedance spectroscopy (EIS). Results As the concentrations of H2 S increased, the passivity and corrosion potentials decreased, while the activity and corrosion current densities increased. The fitting results of EIS showed that (R1 +R2 ) of the base material and the welded zone in TIG joints decreased with the increased concentrations of H2 S. Meanwhile, the welded zone presented lower corrosion potential, passivity, impedance and higher electrochemical activities and corrosion current densities than the base material at the same concentration of H2 S. Furthermore, the results also suggested that the difference of corrosion resistance between welded zone and base material became significant with the increasing concentration of H2 S. Conclusion As the concentration of H2 S increased, the passivation and corrosion resistance of the base material and the welded zone in TIG joints decreased and the difference of corrosion resistance between them became significant. The base material presented higher corrosion resistance than the welded zone at the same concentration of H2 S.