A solution was proposed for locally insulating thermal bridge components of light steel keel systems and various connections in light steel prefabricated buildings through the application of biomass insulation materials. Steady-state heat transfer within relevant application scenarios was simulated using ANSYS Fluent simulation analysis software to evaluate the thermal insulation performance of such materials and investigate the influence of different insulation treatment approaches on thermal bridging effects. The research results demonstrate that implementing biomass insulation materials at thermal bridge locations produces a measurable attenuation effect on thermal bridging phenomena. Through optimized insulation interventions, the affected zones of external wall thermal bridges, exterior-external wall thermal bridges, and exterior-interior wall thermal bridges are reduced by 35%, 4.5%, and 17.6% respectively. Correspondingly, the thermal bridge linear coefficients experiences reductions of 0.07, 0.14, and 0.07 W/(m·K), while significant reductions in heat loss within thermal bridge areas are observed.