Abstract: Through tensile, bending, impact, hardness tests and metallographic structure analysis, the structure and performance of manual arc welding joints of steel for railway freight cars in harsh environments were studied. The results show that the microstructure of base metal is ferrite + pearlite, the weld seam structure is massive proeutectoid ferrite distributed along the grain boundary, and the internal structure is granular bainite, acicular ferrite and pearlite. The superheated zone structure is composed of ferrite and pearlite, and the grains are relatively large. The structures of fine crystal area and the partial transformation area are both fine ferrite and pearlite. The hardness distribution of the welded joint is relatively uniform,ranging from 220HV to 260HV. The welded joint has good tensile, bending, and impact properties. The impact performance of the butt joint at room temperature and-40℃ is better than that of the base material.