Abstract: The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel. The results showed that after upgrading, the volatile content of biochar ranged from 16.19% to 45.35%, and the alkali metal content, ash content, and specific surface area were significantly reduced. The optimal route for biochar production is hydrothermal carbonization–pyrolysis (P-HC), resulting in biochar with a higher calorific value, C=C structure, and increased graphitization degree. The apparent activation energy (E) of the sample ranges from 199.1 to 324.8 kJ/mol, with P-HC having an E of 277.8 kJ/mol, lower than that of raw biomass, primary biochar, and anthracite. This makes P-HC more suitable for blast furnace injection fuel. Additionally, the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits. P-HC offers the highest potential for carbon emission reduction, capable of reducing emissions by 96.04 kg/t when replacing 40wt% coal injection.