The reactive O-containing species in bio-oil could induce the polymerization of bio-oil during its thermal treatment,which affects the relevant utilization of bio-oil significantly,Furans,as the highly reactive O-containing species in bio-oil,play important roles during the thermal treatment of bio-oil.In this study,furfural was chosen as the representative of the furans in bio-oil to investigate its roles during the thermal treatment of bio-oil.The raw bio-oil with and without the addition of extra furfural (10 wt% of bio-oil) and pure furfural were pyrolyzed in a fixed-bed reactor at 200-500 ℃.The results show that the interactions among furfural and bio-oil components can take place prior to the evaporation of furfural (<140 ℃) to form the intermediates,then these intermediates could be further polymerized to form large molecular compounds,and coke can be formed via the interactions at temperatures ≥ 300 ℃ At temperatures ≤ 300 ℃,furfural mainly interacts with anhydrosugars.As the temperature further increases,the aromatics are involved in the interactions to form coke.The increased percentage of the coke formed via the interactions is in a linear relation with the conversion of furfural during the pyrolysis at 300-500 ℃ (no coke formed at 200 ℃).Meanwhile,more non-aromatic light components (≤ C6) and less aromatics in the tars could be formed due to the interactions.