Abstract: Briefed here in the essay are the process and general equipment situation of the piercing mill(CTP)for the seamless steel tube. Addressing the two types of the CTP outlet equipment i.e.,the plug quick change-over equipment,and the plug bar circulation equipment,the configurations and structures are detailed. Comprehensive comparisons between the said two types are made in terms of the production cycle,the shell temperature drop,and the process and the equipment proper. As a result it is concluded that the common advantages of the two types are good plug cooling effect,and consistent inner surface quality of the shell;the plug bar circulation type has its main advantage of quick production cycle,and its disadvantage of rising the shell temperature which leads to such problems as increasing the deformation resistance during the follow-up rolling operation,increasing the deformation difficulty and the energy consumption,and the bigger equipment investment than that of the plug quick change-over type,and meanwhile leads to increasing the difficulty of maintenance of the CTP lower shaft;the disadvantage of the plug quick change-over type is occasionally-happened failure of falling-down of the plug.