Abstract: Taking the gear transmission system of a hybrid model as the research object, the power flow direction and load transfer route of the vehicle dynamic coupling system are analyzed according to different driving conditions. Then, the finite element model of the gearbox is established by combining the gear transmission system with the box, and the first 10 order natural frequencies of the gearbox are simulated by Ansys software to obtain the mode change rule. In order to verify the correctness of the finite element model and the accuracy of the simulation calculation, the modeling test platform is set up for verification. The results are helpful to optimize the structural parameters of the gear system and provide basic data for the NVH characteristics of the gearbox in the later stage.