The heating process of the heavy ingot is nonlinear and the centre temperature of the ingot during heating can not be detected directly. How to formulate a reasonable heating process before forging has become the most important key technical problem to be solved during the heavy ingot forging. The heating process of steel ingot before forging of the marine propeller shaft was simulated numerically by the finite element software Deform-3D. The temperature field and stress field during heating was analyzed, and the safety of the heating process was evaluated. The heating process was further optimized. It shows that the temperature field becomes more uniform after heating by increasing the preservation temperature and the temperature head without an increasing in the heating time and inner stresses.