Abstract: Aiming at the unstable vibration phenomenon caused by the shear flow of lube oil in micro-gap, solving models of journal section temperature difference, rotor thermal bending and rotor vibration were established. Taking the periodic vibration fluctuation of two generator units as research object, the influence of lube oil temperature and unbalanced force on the vibration of turbo-generator was analyzed. Results show that the thermal bending effect caused by the shear flow of lube oil in the bearing micro-gap may cause the unstable vibration of the unit under certain conditions. Properly increasing the oil inlet temperature and sealing pad clearance can reduce the thermal bending deformation of the rotor and reduce the vibration fluctuation. Unbalanced force will excite large whirl track. By using dynamic balancing methods, the difference between the maximum and minimum oil film thickness of the bearing can be reduced, the temperature difference in the journal section can be reduced, and the vibration state can be stabilized.