Abstract: Planetary gears in automobiles are one of the core components of the transmission system, and their failure has a significant impact on the performance and safety of automobiles. This study investigates the failure mechanism of planetary gears through experimental testing and numerical simulation analysis. The numerical simulation results show that the torque and speed of the planetary gears have an important influence on the failure mode and service life. At the same time, the use of high-strength materials and improved design can effectively increase the life of planetary gears.