Automotive gears are the core components of vehicle power transmission, and the hardness level and distribution of the gears directly determine their ability to resist wear, contact fatigue, and other failures. Heat treatment is the key process that imparts the necessary intrinsic properties to metal parts. It allows for changes in the internal microstructure of the material and enhances its strength and toughness. Different heat treatment processes can lead to significant differences in the final hardness, even when the same material is treated, thus affecting the overall performance of the gears. Therefore, this paper explores the gears produced by two heat treatment processes applied in automotive gear manufacturing, aiming to objectively reveal the specific impact of process selection on the final hardness level of the gears, providing a reference for optimizing production processes and ensuring the performance and lifespan of the gears.