Abstract: Analyzed and discussed in the essay are the deformation characteristics of the rolling process of the 2-roll rotary piercing mill. Given that the designed specification of the shell is satisfied，the two principles of having minimum reduction amount and minimum free deformation zone length to ensure piercing quality are analyzed. Accordingly，the theory and calculation method for adjustment of piercing design and adjustment. The analysis leads to such a conclusion that the conventional piercer roll profile can be optimized by means of adopting the completely-new design concept of the piercing roll profile with the 3-section inlet cone，which will get the piercing process further developed in a theoretic and quantitative way instead of the original experiencing and qualitative way.