Two turbine generator units with unstable vibration faults caused by unreasonable bearing elevation distribution are presented. Using the communicating vessel principle, elevation change among bearings with condenser vacuum and power are measured and analyzed. We found that elevation of bearings on low pressure cylinder in high vacuum state is the lowest among bearings. Shaft alignment in the cold state is not unreasonable. We pre-compensated and adjusted bearing elevation in the cold state on the base of the measured bearing elevation data. Vibration faults of two units were solved successfully. Vibration phenomenon, bearing elevation change monitoring data and fault troubleshooting method are presented. It is verified that bearing elevation pre-compensation method for solving such kind of faults is valuable.