Abstract: Sinter hardening property of four kinds of low alloy steels with different composition is investigated. Results show that tensile strength and hardness of sintered low alloy steels increase obviously when elements such as Mo‚, Mn‚, Cr etc are added. Mechanical property of the low alloy steels manufactured by sinter hardening process are better than that by conventional sintering process. With macrohardness reaching HRC35.4 and strength reaching 540.74 MPa. Metallographic observation indicates that after sinter hardening the microstructure is mainly martensite with a few rudimental austenite‚ ferrite and pearlite.