Abstract: The co-refining of acidic palm oil and poplar powder were conducted in supercritical methanol to investigate the effect of reaction temperature and time，stirring speed on the decomposition and gasification rate of wood powder as well as light and heavy oil yields.The optimized reaction conditions are：300—320 ℃ and 15—30 min； the maximum liquefaction ratio is 53.0% under the optimized conditions，and the conversion of the acidic oil is nearly 100%.It was found that the decomposition ratios of cellulose，hemicellulose and lignin are enhanced by 18.9%，11.2% and 25.0%，respectively due to the co-fining with palm acidic oil，compared with the results of direct conversion in supercritical methanol medium.

Key words: bio-heavy oil, bio-oil, co-refining, high pressure liquefaction