Abstract: 316L stainless steel metal fiber were treated with two heat treatments respectively, the first type was the aging treatment of 850 ℃/1 h, the second was to continue heating the sample to 850 ℃for 5 min after the first heat treatment, and water-cooling, quickly cooled down to 0 ℃. The characteristics of the two samples were observed after heat treatment. The results show that, after the first heat treatment, the metal fiber precipitates the carbide Cr₂₃C₆, NiC, and NiFe phases, among them, Cr₂₃C₆ is the main precipitated phase, which can reduce the average fracture strength and fracture elongation by 4.58 cN and 3.99% compared with that of the normal soft state. After a second thermal treatment, the metal fibers undergo a phase transition to form a small amount of martenite, but the martensite causes a strong increase in metal fiber breakage. Both carbide Cr₂₃C₆ and martensite can cause the decrease of corrosion resistance of metal fibers.