The valve stem oil seal is an oil seal accessory used on the valve stem of an automobile. The valve stem is not only a moving part, a stress part, but also a sealing part during the opening and closing process of the valve. At the same time, it is impacted and corroded by the medium, and it also generates friction with the filler. Therefore, when selecting the valve stem material, it must be ensured that it has sufficient strength, good impact toughness, scratch resistance, and corrosion resistance at the specified temperature. The valve stem is a vulnerable part, and attention should be paid to the machining performance and heat treatment performance of the material when selecting it.