Proposed is a lumped parameter model of gear transmission systems.In this model,firstly,lumped parameters of the housing are extracted from housing's finite element model via a sub-structure method.Secondly,the modal parameters of the foundation are extracted from foundation's acceleration by means of indirect physical parameter identification.Then,the extracted modal parameters are transformed into lumped parameters,and a dynamic model of the gear-housing-foundation coupled system is established according to interface coordination conditions.Finally,by taking a single-stage helical gear system for example,the gear's dynamic transmission error,the bearing's reaction force and the housing's vibration of the coupled system are simulated under the excitation of time-varying mesh stiffness.The system dynamic analyses before and after the coupling of housing and foundation show that both housing and foundation only have limited influence on gear's dynamic transmission error,but significantly affect the bearing's reaction force fluctuation and the housing's vibration; and that the proposed coupling model can predict the system's dynamic characteristics than the uncoupled one more precisely.