Poplar was liquefied using the mixed solvents of PEG 400/glycerol catalyzed by sulfuric acid under microwave heating,and liquefied wood-based polyurethane foams（PU）were prepared from the liquefied wood products and 4,4′-methylene-diphenylene isocyanate.The results indicate that microwave heating is a promising effective alternative method for traditional heating in wood polyhydric alcohol liquefaction.The optimal conditions for microwave-assisted liquefaction of poplar wood with polyhydric alcohols are as follows:moisture content 4.7%,microwave power 500 W, polyol to wood ratio 2.5,liquefaction time 15 min.The liquefied wood-based PU foams showed apparent density of 0.038g/cm3 and compressive strength of 68kPa respectively.