In order to obtain accurate dynamic response analysis of planetary gear transmission systems，an accurate
product design should be performed． In this paper，a dynamic model of 2K-H planetary gear transmission (PGT) system coupled with gearbox vibrations is constructed，in which the whole system is divided into the transmission part and the gearbox structure，and the modeling of the transmission part and the gearbox structure are conducted respectively by means of the lumped mass method and the finite element method． Then，the gearbox model is transformed into the joint nodes of bearing supports through the substructure method and is coupled with the transmission system under the interface coordination condition． Moreover，the time-varying mesh stiffness and the mesh error are also taken into account，and thus a time-varying multi-degree-of-freedom-coupled dynamic model of planetary gear transmission system is constructed． The system dynamics analysis results before and after coupling gearbox show that (1) the coupling of gearbox reduces the meshing forces and supporting forces of planetary gear transmission system markedly; (2) the change of rotor speeds causes the meshing forces and the supporting forces to change in
different directions when other system parameters are invariant; and (3) in order to achieve the light weight design and reliability design of the optimized transmission system，it is necessary to finish accurate dynamic modeling and analysis．