AbstractMicrowave heating was applied in the liquefaction of corn stover with polyhydric alcohol to establish a rapid process for converting corn stover into polyols. With ethylene glycol (EG) as liquefacient and 3.5% sulfuric acid as a catalyst, the residue content was reduced to 4.7% after 20 min of microwave liquefaction at 160 °C. Effects of liquefaction parameters on the residue content were investigated. It was found that the reaction temperature had a greater influence on the residue content than the sulfuric acid concentration and reaction time. The liquefied mixture was characterized as complexes of ester and ether type polyols by means of Fourier transform infrared spectroscopy. 3-(2-Methyl-1,3-dioxolan-2-yl) propanoic acid was characterized as the main degradation product of corn stover, besides the large amount of condensation product of EG.