In this paper, the influence degree of eccentricity distance and guide bearing stiffness change on the vibration characteristics of the unit under the condition of rotor mass misalignment is discussed respectively, and the modal characteristics of the unit are studied for the problem of generator mass eccentricity. First of all, the guide bearing is parameterized, the whole axle system modeling is calculated by FEM modal analysis method, the results of the analysis obtain the first 10th order critical frequency and vibration mode analysis results, further determine the danger point of displacement deformation concentration. Comparing the vibration type, critical frequency and center vibration trajectory of the guide bearing under different constraint conditions, the characteristics of the unit vibration caused by the rotor quality is: the axis tile gap is gradually enlarged due to the eccentric rotation of the rotor of the unit, and the vibration characteristics of the main frequency in the unit vibration signal are unchanged. The results are confirmed by field inspection data.