fluidized combustion within the furnace. The preheating modifications of woody biomass particles under different preheating temperatureswere examined using a kilowatt level preheating combustion test rig. BET, SEM scanning electron microscopy and Raman spectralband comparison methods were employed to detect and analyze the specific surface area, total pore volume, nitrogen isothermal adsorptionand desorption characteristics, particle morphology and other key physical property parameters of high temperature biomass semi-coke.The findings indicate that an increase in preheating temperature results in a noticeable rise in nitrogen adsorption amount, suggesting thatthe modified biomass semi-coke possesses a more developed pore structure. The depolymerization and devolatilization of pine biomass particles at high heating rates, combined with the analysis of carbon microcrystalline structure, result in the disruption of macromolecular carbon chains and the generation of small molecular volatiles, thereby enhancing reactivity. The modified high - temperature biomasssemi-coke exhibits rapid attainment of stable combustion within the descending combustion chamber, with a remarkable combustion efficiency reaching 99% in terms of its combustion characteristics. In terms of NO emissions, the combustion temperature is maintained at1 100 ℃ under all experimental conditions to prevent the formation of thermal NO. It is noteworthy that the concentration of NO emissions from pine biomass particles does not exhibit a linear relationship with preheating temperature. Specifically, at 842 ℃ , the concentration of NO emissions peaks and then begins to decrease. Within the range of test temperatures, when the preheating temperature is set at705 ℃ , the concentration of NO emissions reaches its lowest value, namely 97.79 mg/ m. In conclusion, for ensuring low NO emissionsand high combustion efficiency in pine biomass after preheating combustion, this study recommends an optimal preheating temperature of705 ℃ .