To explore coupling characteristics of hydrodynamic lubrication and gear transmission system under line contact,the generalized finite element method was used to establish two stage gear transmission system.The mesh stiffness was solved through the finite element method.Considering the oil film stiffness effect under gear lubrication condition,gear oil film stiffness and mesh stiffness were superposed comprehensively,the dynamic equation was solved using Newmark integration method.The dynamics and lubrication characteristics of gear meshing positions under different working conditions after coupling lubrication were analyzed.The results show that the comprehensive stiffness of gear decreases with the increase of rotational speed and increases with the increase of load;rotational speed has a greater influence on the oil film thickness than the load;considering the flexibility of the shaft,the amplitude of the transmission system changes significantly in the resonance speed region,which will have a certain impact on the oil film thickness and system vibration;after coupling the oil film,the dynamic load on the tooth surface changes significantly in the high-speed resonance region.