The axial flux permanent magnet (AFPM) motor severs as a passive magnetic bearing and works in parallel with the gas foil bearings (GFBs), while it outputs a circumferential electromagnetic torque to the rotor system. When the single statorsingle rotor AFPM motor supproted by GFBs suffers from a sudden change of rotating speed, the impeller or turbine generates a transient axial force acting noto the rotor. To reveal the effect of the axial shock on the vibration of the rotor system, a rigid rotor dynamic model of the single stator-single rotor AFPM motor supported by 2 radial GFBs and 1 axial GFB was established, considering the axial attraction force, radial restoring force of the PM and the thrust of the axial GFB. Results show that the influence of the axial impact on lateral vibration is very small, the nonlinear stiffness of the foil affects both the amplitude and time of rotor oscillation, and the axial amplitude increases with the increase in the absolute value of PM negative stiffness. A reasonable matching among PM stiffness, structural stiffness and damping of the foil is important to ensure that the time and amplitude of rotor oscillation under the axial impact do not exceed the allowable value.