In response to the problem of excessive vibration of the supporting motor of a large vertical pump unit in a nuclear power plant, through frequency spectrum analysis and combined with the trend of vibration data in the past six months of the pump unit, it is determined that the synchronous vibration frequencies of 14.5 and 15.5 Hz are not caused by motor body faults, but by friction between the pump body guide bearings. The correctness of the judgment has been verified through disassembly inspection. Considering the repeated occurrence of friction in the guide bearings of the pump unit, combined with the structural resonance problem of the pump unit itself, the fundamental cause of friction failure in the guide bearings was analyzed. An innovative application of tuned mass dampers was proposed for vibration control of the pump unit. At the same time, the abrase data of the guide bearings of three pump units were compared, and it was found that the vertical guide bearing friction coupled structural resonance pump unit was subjected to vibration control by installing tuned mass dampers, not only can it reduce high vibration faults caused by structural resonance, but also it has a good effect on alleviating friction in guide bearings.