The cable layer ventilation system (DVE system) of multiple units in a nuclear power plant has many motor bearing failures. The motor of DVE system provides appropriate ventilation services for the cable, battery, reactor protection system (RPR) equipment and other related equipment installed in the cable layer. If the DVE system fails, it may cause air exchange conditions and environmental temperature deterioration, cause the unavailability of nuclear island system and equipment, and affect nuclear safety. Aiming at this problem, through carrying out vibration spectrum analysis, visual inspection analysis, detection analysis, bearing load calculation and bearing life calculation for the failed bearing, locking the root cause of the bearing failure, and formulating reasonable and feasible corrective measures, finally overcoming the technical problem to ensure the safe and stable operation of the nuclear power plant. At present, the calculation and analysis method has been extended to a nuclear power group to ensure the equipment safety of similar systems in nuclear power plants under construction and operation.