Abstract: A mathematic model of the rolling torque is set up with which the law of influences as produced by the key process parameters during the 2-roll rotary piercing process. It is revealed via the research that the roll space and the plug extension amount are obviously corrected with the rolling torque,and corrected with feed angle positively. And the quantitative analysis shows that when the billet temperature drops from 1 230 ℃to 1 130 ℃,the rolling torque is tremendously increased by 85.09%,while when the roll space is decreased from 265 mm down to 245 mm,the rolling torque is increased by 38%. Comparatively both the billet temperature and the roll space affect the rolling torque mostly. The interaction mechanism between the process parameters and the rolling torque is revealed via the research,which provides a theoretic basis for optimized setting of the process parameters during the actual production,and has important guiding significance for reducing energy consumption as well as enhancing the productivity.