Abstract: As the steam turbine generator set in a circulating fluidized bed for low pressure cylinder rotor is replaced by pure coagulation rotor operation, the vibration values of the No.3 and No.5 pillow shaft vibration and the bearing are larger and the signs of fluctuations exist. It is analyzed that the vibration value of the bearing box is reduced to the qualifying range by means of increasing the dynamic stiffness of the bearing seat and adjusting the parameters of the shaft system. The treatment improves the unit's safe and reliable operation ability and prevents the unplanned shutdown, and ensures the safe and reliable operation of the unit.