Abstract: In view of the abnormal vibration phenomenon during commissioning of a coaxial drive feed water pump turbine equipped with Vorecon transmission equipment, the bearing vibration, start-up process parameters, dynamic and static friction fault mechanism and Vorecon lubricating oil pressure were analysed. Calculation and analysis results show that the abnormal vibration is caused by many factors, including the low load of shafting, dynamic and static friction and oil film instability. To solve these problems, a series of measures were taken, including increasing the shaft seal temperature, extending the warming-up running-in time, reducing the lubricating oil pressure, and shortening the operation time of the coaxial feed water pump. Results show that, compared with the first start-up of the unit, the amplitudes of bearing No.1, 2 and 3 and Vorecon input shaft decrease from 164.08, 283.92, 217.48, 110 μm to 19.90, 24.47, 22.15, 47 μm respectively, and the abnormal vibration phenomenon is eliminated. The vibration data of each bearing are normal under no-load, low-load and full-load operation conditions.