Abstract: In this study, FA was extracted from lignite of Xianfeng coal mine by mixed oxidation with H₂O₂ and alkali, and the effects of different alkalis (NaOH and KOH) on FA extraction were investigated under the oxygenation activation of H₂O₂. KOH+H₂O₂ was selected for the mixed oxidation and extraction of FA, and the reaction rate was controlled by the addition of antifoam agent dropwise, and the conditions of extraction were optimized, and the FA yield was up to 40.00% under the optimal conditions (2.5 h at 50 ℃). The structures of FA extracted under different conditions were analysed by UV, IR and TG, and it was found that the FA extracted by KOH+H₂O₂ oxygenation method was rich in functional groups, small molecular weight and low unsaturation, and the roles of K⁺ and H₂O₂ in the extraction process were reasonably speculated. FA was cleaved using Py-GC/MS, and the structural composition of FA was analysed by the cleavage products, which suggested that FA might be composed of structures such as acetic acid and 3 furfural, and also had a small molecule of serine that was directly extracted. Based on the characterisation results, the oxidation reaction process of bridge bonds, oxygen-containing functional groups, and unsaturated bonds was proposed to provide implications for the resourceful utilisation of lignite and the mixed-oxygen cleavage to improve the FA yield.