Purpose <p>To analyze the vibration characteristics associated with coupling failures in permanent magnet synchronous motors due to bearing inner ring misalignment and rotor declination eccentricity, a finite element model of the rolling bearing-rotor system dynamics was developed.</p> Methods <p>A nonlinear hybrid eccentric unbalanced magnetic pull model and a nonlinear bearing restoring force model, accounting for the declination angle misalignment of the bearing inner ring, were established. The vibration characteristics of the system under fault conditions are analyzed through various vibration responses, including spectrum diagrams, time domain waveform diagrams, and phase plane diagrams.</p> Results <p>The results indicate that, under such faults, the unbalanced magnetic pulling force and the bearing restoring force are coupled, resulting in a system that exhibits complex vibration characteristics. As the failure rate increases, the vibration response shows a distinct trend of change. Furthermore, this study examines the influence of the bearing's radial initial clearance on the vibration characteristics of the faulty system.</p> Conclusion <p>Research indicates that when a coupling fault occurs, the rotor system exhibits complex frequency-multiplying components. Furthermore, there are combined frequency components associated with the variable compliance (VC) of the bearing and the rotation frequency within the system. As the fault angle increases, the amplitude of the rotor rotation frequency decreases significantly. This phenomenon occurs because the bearing restoring force increases substantially with the deflection angle, thereby suppressing vibration in the rotor's normal direction. Additionally, alterations in the initial radial clearance of the bearing lead to significant changes in the amplitude of each frequency component.</p>