To clarify the reaction pathways of condensed residues and the structural characterizations of liquefaction products at the stages of decomposition and condensation reaction during wood liquefaction, wood powder(Betula dahurica Pall.) of 40-80 mesh was liquefied at 150℃and 0-180 minites. The ratio of polyhydric alcohols to wood to acid was 3:2:0.03. Liquefying reagents was polyhydric alcohols (PEG400:glycerin=4:1). The catalyst was sulfuric acid (concentration of 72 percent). The methods such as FTIR, XRD, ...