Aiming at the difficulty in demoulding of electrode block and the problem of non-uniform density distribution of electrode block produced by 80 MN hydraulic press machine. The stress field,principal stress field and velocity field of punch and electrode block during the demoulding process were analyzed. Besides,the friction force of electrode block was also quantitatively analyzed. Finally,the reasons for difficulty in demoulding were found via the finite element software. On this basis,the punch surface shape was optimized. The strength at the sharp corner of the optimized punch,demoulding process and average density distribution of the electrode block were simulated and analyzed. The production practice shows that the optimized punch not only completely solves the problem of the electrode block demoulding,but also improves the non-uniform density of the electrode block.