In order to investigate the dynamic characteristics of the oil film under vibration,considering the excitation effect of the timevarying meshing stiffness of the gear,based on the dynamics theory,the dynamic model of the gear system was established,and the elastohydrodynamic lubrication(EHL) characteristics of the gear system were analyzed.Based on the numerical solution of EHL,the stiffness model of the oil film was established to carry out the coupling study of gear dynamics and oil film lubrication at different rotating speeds.The results show that when the dynamic model is used to solve the EHL,the oil film thickness shows certain dynamic characteristics,and the vibration amplitude and vibration frequency are different under different gear speeds.As the gear speed increases,the stiffness of the oil film is decreased.For highspeed and heavyduty gear systems,oil film lubrication has a great influence on the vibration characteristics of the gear system.The vibration of the gear and the oil film lubrication should be considered as a whole.