Abstract: The DBTT of high nitrogen austenitic stainless steel 1Cr22Mn15N was tested between room-temperature and -200℃ by tensile test and Charpy-type test,and the ductility and brittleness transition of it was investigated under low temperature by the SEM,TEM and XRD methods.The results show that for 1Cr22Mn15N,the DBTT is about -110℃.Brittle fracture occurrs first at -80℃.The change of fracture patterns of high nitrogen austenitic stainless steels is dimple→dimple+quasi-cleavage fracture→cleavage fracture,and fracture mode is transgranular fracture.ε-martensite is observed by TEM in brittle transition austenite and induced along 111γ plane.