In the research field of face gear transmission system, most of the research objects are single-stage face gear pairs, and there are relatively few research contents on the dynamic characteristics of face gear split-confluence transmission system. Focusing on the nonlinear dynamic characteristics of the aviation non-orthogonal offset face gear shunt system, the mathematical models of bearing rolling element deformation, tooth side clearance and comprehensive transmission error are established, and the multi-degree-of-freedom coupling bending-torsion combination dynamic model of non-orthogonal offset face gear transmission including bearing is derived. The vibration differential equation of the non-orthogonal offset face gear flow separation and confluence system is solved by numerical method. The nonlinear dynamic characteristics of the complex system are studied by combining the time domain diagram, frequency domain diagram, phase diagram, Poincaré map, Lyapunov exponent and bifurcation diagram. The influence of excitation frequency and meshing damping ratio on the displacement of the meshing line between the shunt stage and the confluence stage gear pair is studied. The results show that the shunt stage and the confluence stage of the system show different nonlinear characteristics under specific parameters. With the increase of excitation frequency, the shunt stage appears single-period, multi-period and chaotic phenomena, while the confluence stage does not have chaotic phenomena. With the increase of meshing damping ratio, the state change of the shunt stage is similar to the inverse period doubling bifurcation process, while the confluence stage may also maintain a periodic motion state at a smaller damping ratio. Therefore, reasonable excitation frequency and meshing damping ratio can make the system jump out of chaos and remain stable, which provides a theoretical basis for fault prevention and fault diagnosis of face gear split-confluence transmission system. At the same time, it provides a reference for the design of face gear split-confluence transmission system and the selection of lubrication conditions.