Abstract: The simulation test and investigation for the samples of weldment were performed under high temperature sodium vapor at 400 ℃ for 3 000 h. The samples were welded by 08X16H11M3 austenitic stainless steel produced in Russia and 304 austenitic stainless steel produced in China. The measurement and analysis of the corrosion rate, corrosion products, surface micro-morphologies, the composition at grain-boundary were performed for the samples pre- and post- tests, and the results show that there are no inter-granular corrosion which can be observed at the surface contacted with sodium vapor. There are obvious elements diffusion at the surface of 304 stainless steel matrix, but it has no visible influence on the structure of matrix and mechanical properties of the material.