Abstract: To determine the ability of the three-roll pipe mill for reducing the shell’s eccentricity,the roll deformation zones’characteristics in reducing eccentricity of the pierced shell were systematically analyzed with the elementary analytical method.Furthermore,experimental operations were conducted to investigate how the three-roll pipe mill reduces the eccentricity of pierced shells with heavy/medium/light W.T.s.The research result shows that the three-roll pipe mill provides the best eccentricity reducing effect on shells with rather heavy walls and that O.D.reducing section fo the roll deformation zone plays a major role in shell eccentricity reduction,while both W.T.reducing section and finishing section of the zone provide so little effect on shell eccentricity reduction that only one nineth reduction of the original shell W.T.can be obtained.