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In the present work,ball milling was applied for the pretreatment of lignocellulose to obtain high conversion and bio-oil yield in supercritical ethanol.Ball milling substantially decreased the crystallinity and particle size of lignocellulose,thereby improving its accessibility in ethanol solvent.An increased bio-oil yield of 59.2％ was obtained for the ball milled camphorwood sawdust at 300℃C,compared with 39.6％ for the original lignocellulose.Decreased crystallinity significantly benefited the conversion of the cellulose component from 60.8％ to 91.7％,and decreased particle size was beneficial for the conversion of all components.The obtained bio-oil had a high phenolic content,as analyzed by gas chromatography-mass spectrometry.Methoxylation and retro-aldol condensation were observed during alcoholysis,and the reaction pathways of lignocellulose in supercritical ethanol were attributed to the action of free radicals.