Expansion is an important operation in the hot extrusion production line of seamless steel tubes,which is to produce proper hollow billets for extrusion.The billet goes through induction heating before expanded to acquire a proper temperature.In this study,the effects of three types of inhomogeneous temperature fields on 321 stainless tubes during the expansion process were simulated.The results have indicated that it was an optimum temperature filed for expansion,where the temperature varied linearly along radial direction and the temperature was lower on the inner surface.This temperature field is beneficial to improving the stability of expansion and ensuring dimensional accuracy and increasing the utilization rate of tubular billet material.