The nonlinear dynamic model of the non-orthogonal face gear-rotor-bearing system with time delay feedback is established considering the factors of time-varying meshing stiffness， transmission error， tooth backlash， and the fluctuation of input torque. In addition， the multi-scale method is used to analyze the primary resonance characteristics and determine the stability conditions of the system. The effects of time delay parameters， meshing damping， time-varying meshing stiffness， and load on the primary resonance of the system are studied by numerical methods. The results reveal that the control parameters should be selected reasonably to avoid excessive primary resonance amplitude and unstable branches. A reasonable meshing damping is beneficial to suppress the amplitude of the primary resonance and reduce the unstable branches， and an excessively high excitation frequency is easy to produce unstable branches of primary resonance. The unstable branch of the primary resonance gradually decreases with the increase of the fluctuation of the meshing stiffness， but when the excitation frequency is close to the primary resonance frequency， a small fluctuation of the meshing stiffness will also cause the system to be unstable. In addition， the increase of load fluctuation will increase the primary resonance amplitude of the system， and will damage the stability of the system.