Abstract: Auxiliary motors driving fans, coal feeders and circulating pumps in circulating fluidized-bed units operate continuously, and bearing abnormalities generally involve both frictional heating and changes in structural loading. A three-dimensional sequential thermal-structural model comprising a shaft, inner and outer rings, equivalent rolling elements and a cage was established. Normal, equivalent increased-clearance, equivalent lubrication-degradation and 30% overload conditions were considered. The maximum temperatures were 77.95, 79.59, 115.91 and 89.34 °C, and the maximum equivalent stresses were 71.84, 75.26, 141.43 and 93.39 MPa, respectively. A combined condition index based on normalized temperature rise and equivalent stress was used to characterize the relative condition of the four cases. The results provide a reference for bearing condition monitoring and maintenance-priority decisions for auxiliary motors in circulating fluidized-bed units.