<p>To improve the problems of difficult hot forging and insufficient filling caused by complex shapes and the large size of large modulus spiral bevel gears, this paper proposes a multi-step hot forging process of spiral bevel gears by analyzing the forming characteristics of parts structure. Firstly, the influence of workpiece temperature, die movement speed, and die transition fillet on the filling rate, stress value, and strain value of pre-forgings is analyzed using Deform-3D software and the single-factor experiment method. Secondly, the mapping relationship model between the process parameters and the forming effect is established based on the response surface method. The average stress of the gear and the difference between the ideal forging and the actual forging filling area are proposed as the optimization objectives, and the multi-objective optimization of the pre-forging process parameters of the spiral bevel gear is carried out. The optimal process parameters are as follows: the billet temperature is about 1200 °C, the mold movement speed is 150mm / s, and the mold transition fillet is 2mm. Finally, the process experiment is carried out under the optimized parameters to verify the reliability of the optimization results. The results show that the optimized process parameters can effectively improve the metal filling effect of spiral bevel gear pre-forgings and improve the forming accuracy of gear final forgings. This study can provide a reference for formulating the hot forging production process of large modulus spiral bevel gears.</p>