As the core power connection component of the transmission system, the through shaft undertakes the tasks of long-distance torque conduction and power distribution, and has two core highlights: large transmission torque and impact resistance. The transmission torque performance is excellent, using 42CrMo high-strength alloy steel integral forging process, the shaft diameter is optimized by finite element simulation, the torsion section coefficient is optimized and increased by 25%, and the rated transmission torque is more than 30% higher than that of conventional shafts of the same specification, which can stably carry high-power power transmission. The impact resistance is outstanding. After comprehensive treatment of integral quenching and tempering and surface quenching, the shaft hardness reaches HB280-320, the impact toughness of key stress areas is ≥85J/cm2, and with the shaft shoulder fillet transition reinforced structure, it can resist instantaneous impact loads during vehicle shifting and construction machinery operation, reducing the probability of fracture failure.