Abstract: Experimental studies are made on the development process of metallographic structure and the structural form of the 15Cr2Ni3MoW alloy steel to identify the structural characteristics of the steel, the proper structure types suitable for the hi-performance requirements of the piercing plug as well as the relationship between the steel structure types and their operation performances. It is required for the plug made with the 15Cr2Ni3MoW alloy steel to be of homogeneous compound structure consisting of fine bainite grains and a small amount of martensite grains and have dense surface oxide film which is mainly composed of FeO and combined firmly with the base metal. The operation practice of the plug made with the modified manufacturing process demonstrates that thanks to its changed metallographic structure, the plug is now in possession of such advantages as higher hardness, 45% increased impact energy and over 50% longer service life.