Abstract: The phase structure and high toughness of powder sintered biphase stainless steel and after its ageing have been studied. Results have shown that biphase stainless steel with 18vol% ferrite and austenite can be obtained by adding 4 wt% Si in 316L powder using powder sintering process. After ageing at 800℃, a strip-shaped phase was precipitated along the interface between austenite and ferrite of the biphase stainless steel and that made the hardness of biphase stainless steel increase and plasticity decrease.