Abstract: The article introduces the die-forging process for and the profile design of the piercing plug.Both the profile and manufacture quality of the plug are in direct connection with tube quality.With die forging process, the plug is formed directly by means of forging-drawing operation, requiring no machining which means low metal loss and high yield.Moreover, the plug made with the said process posseses compact surface oxide film, needing no heat treatment and having a long service life.