A vibration analysis modeling method was presented to analyze the vibration of multi-rotor system geared by angular spiral bevel gear pairs.The vibration equations of a single-rotor system were obtained using the vibration equations formula of each node with six degrees of freedom.The global vibration equations of the entire geared multi-rotor system are established through the whole coupled matrixes of the angular spiral bevel gear pairs.The nature frequencies,critical speeds,amplitude-frequency diagram and whirling orbit etc,were obtained by analyzing the global vibration equations of multi-rotor system.The numerical analysis showed that the system produced some new modes and the exciting forces on a rotor of the system would evoke considerable responses of the other rotors for the gears mesh.The numerical example indicated that the whirling orbits of each node varied with the shaft angle of the spiral bevel gear pairs.The effect of the shaft angle must be taken into account when analyzing the vibration behavior of the geared multi-rotor system.The feasibility and the reliability of the method proposed for vibration analysis of geared multi-rotor system are proved by the numerical example.