Abstract: With a large-scale non-linear FE analysis software,a 3D thermal coupling simulation of the loading state of the two-high rotary piercer plug during piercing the round billet is conducted,focusing on the model of surface stress distribution under thermal coupling condition and also covering analyses of other facets concerning the plug such as failure mechanism,material model and thermal transmission boundary conditions,etc.The result of the said simulation is in compliance with that of relevant experiment.