Upsetting, a typical hot deformation process, is simulated by using rigid-viscoplastic finite-element method, its instantaneous stress distribution over the interface between the die and workpiece being derived for the finishing upsetting stage. Based on these computations and in conjunction with elastic finite element method,die strength is then analysized. An optimization design for prestressed die inserts is adopted to decrease pressure being applied to the working surface of upsetting die,and in turn,to prolong its service life.