As a power hub component of the transmission system, the through shaft takes impact resistance and large transmission torque as its core performance highlights. The impact resistance is achieved through a composite process. After integral forging with 42CrMo alloy steel, through integral quenching and tempering and surface quenching treatment, the shaft hardness reaches HB280-320, the impact toughness of key stress areas is ≥85J/cm2, and the shaft shoulder fillet strengthening design can effectively buffer the instantaneous impact load during vehicle shifting and construction machinery operation. In terms of transmission torque, the shaft diameter is optimized by finite element simulation, the torsion section coefficient is increased by 25%, and the rated transmission torque is more than 30% higher than that of conventional shafts of the same specification, ensuring stable transmission of high-power power.