Abstract: Described here in the article is the process for the after-roll change adjustment of the rolling force curve of the 6-stand,3-roll mandrel mill.It is summarized that the adjustment method has to follow the principle of“three-step adjustment method”and the“pass adjustment the primary,rotation speed adjustment the secondary”practice;compared with the 2-roll MPM,in case of slightly steel-pulling,adjusting the rolling force curve of the 3-roll mandrel mill can avoid getting the work-piece concave or broken.Analyzed here are the characteristics of the rolling force curve in case of failure of breaking of the pipe as being rolled in case of roll breaking or roll slipping.Also the causes for failing to getting the pipe stripped off the mandrel are analyzed,and relevant fixing method described.