Abstract: Aiming at the leaking problem of the TIG welded joint between martensitic and austenitic stainless steels used in shipping facilities.Changes of microstructures and the microhardness distribution at different zones in the welded joint between 1Cr17Ni2 and 1Cr18Ni9Ti stainless steels were analyzed by optical microscope, scanning electronic microscope and microhardness tester.On the side of 1Cr17Ni2 base metal, ferrite became coarser in HAZ adjacent to the weld and its microhardness was relatively lower.At the zone in HAZ where the heated temperature was higher, martensite with high microhardness was obtained because of fast cooling.The fracture on the 1Cr17Ni2 side was cleavage and quasi-cleavage mixture, which confirmed that the HAZ of 1Cr17Ni2 base metal was the weakest area in the joint to result in the crack and leakage.The other failure reasons were also analyzed and the measures were put forward to solve the problem.