Abstract: The extreme meteorological environment coupled with strong winds and sandstorms has put forward higher requirements for the wear resistance of transmission line fittings. The partitioning heat treatment process was applied to Si-Mn alloy steel to improve its wear resistance. The equilibrium phase composition and mechanical properties of the Si-Mn alloy steel were simulated by JMatPro software. The CCT curves of Si-Mn alloy steel at different austenitizing temperatures and the phase structure at different cooling rates were analyzed. The heat treatment process of Si-Mn alloy steel was determined according to the CCT curve, and the partitioning treatment test was carried out. The results show that the equilibrium phases of Si-Mn alloy steel are mainly ferrite, cementite, some carbides and borides. The austenitizing temperature range of Si-Mn alloy steel is 780 ℃-1340 ℃. With the increase of austenitizing temperature, the ferritic transformation zone of the alloy steel gradually decreases and disappears, while the bainite transformation zone is basically unchanged. When the cooling rate of the sample is bigger than 1 ℃/s, the microstructure of the sample is basically the same and the mechanical properties have no obvious change. After partitioning heat treatment test, the microstructure of Si-Mn alloy steel is mainly composed of martensite and residual austenite at room temperature, the martensite is mainly lath martensite and massive martensite, the residual austenite is mainly in thin film and cluster forms. The Si-Mn steel has good mechanical properties and wear resistance.