Abstract: In order to accurately study the nonlinear dynamic characteristics of NW （internal and external meshing planetary gear train） wind power transmission system， this paper considers factors such as random wind speed， time-varying support stiffness， ring gear flexibility， time-varying meshing stiffness， transmission error， tooth flank clearance， and bearing clearance. A nonlinear dynamic model of the NW planetary gear-bearing system is established. Time history， FFT spectrum， Phase diagram， and Poincaré maps are used to describe the nonlinear characteristics of the system， and bifurcation diagrams and the maximum Lyapunov exponent are used to describe the influence of excitation frequency and meshing stiffness on the nonlinear behavior of the system in more detail. The results show that the NW planetary gear-bearing system has rich nonlinear characteristics. In a specific range of excitation frequencies， the system can enter a chaotic motion state， leading to instability. However， within a certain range of meshing stiffness， the system can operate stably.