Abstract: In order to study the lubrication characteristics and dynamics characteristics of the gear transmission system of wind turbines,the two-stage fixed-axis gearbox in the SQI wind turbine transmission system experimental platform is taken as the research object,and the gear oil film stiffness,gear mesh stiffness and bearing time-varying stiffness are comprehensively considered. Taking into account the flexibility of the shaft and using the finite element method to establish a multi-degree-of-freedom involute spur gear dynamic model,the Newmark integration method is used to solve the dynamic characteristics of the two-stage gear transmission system under multi-source time-varying excitation. The effects of different working conditions on the stiffness of the oil film are discussed,and the system’s lubrication characteristics,natural frequencies and vibration modes are studied. Studies have shown that the gear meshing rigidity is reduced after considering the gear lubrication effect,the system dynamic characteristics tend to be sensitive,and the inherent characteristics of the system have changed. Among them,the influence on the 11th order is the most prominent. However,the tendency of inherent characteristic changes is weakened near the resonance speed of the system.