The flow-induced vibration of wire-wrapped rod bundles in lead-bismuth cooled fast reactors was caused by coolant erosion, which subsequently leads to fretting friction between the wire wrap and cladding, ultimately resulting in cladding wear. Previous studies has not comprehensively considered the influence of thermal power conditions on flow-induced vibration characteristics. In view of this, a fluid-structure-thermal tri-field coupling methodology was employed to systematically examine the flow-induced vibration phenomena of a single wire-wrapped rod in lead-bismuth cooled fast reactors. The vibration characteristics under different inlet temperature conditions were analyzed through numerical simulations, with both flow field parameters and structural deformation features being obtained. The results reveal that significant variations in vibration amplitude and modal patterns are observed when temperature-dependent mechanical parameters of the wire-wrapped rod are considered. Enhanced vibration amplitudes are identified under conditions of higher thermal loads and lower heat transfer coefficients. Fluid force fluctuations are demonstrated to constitute one of the primary mechanisms responsible for vibration intensification. Although the wall thermal power distribution is found not to alter the fundamental vibration modes, its indirect influence on vibration amplitude is achieved through thermal-structural interactions affecting both fluid dynamics and solid domain temperature fields. These findings are systematically organized to establish an optimized theoretical framework that provides a scientific basis for the improvement of core design and spatial configuration in lead-bismuth cooled fast reactors. The proposed methodology and derived conclusions are validated to offer effective solutions for mitigating flow-induced vibration challenges in advanced nuclear reactor systems.