Abstract: The stress corrosion cracking (SCO of 316Ti and 316NG is studied in acidic SO42- madium by slow strain rate test (SSRT). The results show that sensibility index of SCC of two austenitic stainless steels increase with increasing of the mass fraction of SO42- in madium, and the SCC critical mass fraction of SO42- for 316NG is higher than that for 316Ti, but crack propagation rate of 316NG is quicker than that of 316Ti. The pitting corrosion of two austenitic stainless steels is researched by noble polarization test, the pitting potential of 316NG is higher than that of 316Ti. The SSRT-SCC mechanism is analyzed based on the microcosmic structure and test data.