Aiming at such problems as excessively fast combustion reaction rate caused by the large specific surface area and developed pores of biochar alternative to fossil fuels for iron ore powder sintering, the self-produced sintering flue gas and Ca(OH)₂ solution are used to modify biomass charcoal. The pore size of biomass charcoal is filled by sediment CaCO₃, the specific surface area is reduced, the combustion reactivity is inertized, and the biomass coke is prepared by using modified biomass charcoal and coal-based fossil fuels to ensure the consistency of fuel combustion concentration, so as to improve the substitution ratio of iron ore powder sintering biomass fuel. The results show that most of the pore size of biomass charcoal is filled after being modified by sintering flue gas and Ca(OH)₂ modified solution, and the specific surface area is reduced from 82.736 m²/g to 5.229 m²/g, and the combustion process of biomass coke prepared from coal-based fossil fuels is limited by hindering the oxidation reaction by the modifier, obeying the formula G(α) = -ln(1-α), the reaction exothermic is slow, and the exothermic temperature range is between 400~760 ℃, which close to fossil fuel performance and are conducive to increasing the amount of sintering biomass fuel added to iron ore powder.