Abstract: The alcoholysis of lignin through liquefaction with ethylene glycol was explored. The milled wood lignin (MWL) from Populus tomentosa Carr. was applied and the analysis of lignin structure alteration before and after alcoholysis was conducted with the aid of FT-IR and 1H NMR. It is showed in the results that lignin in P. tomentosa is of GS type, and G/S ratio 1.37. Alcoholysis of lignin caused the cleavage of most β-O-4 linkages and some methyl ether bonds, which lead to a great increase of phenolic structures in the lignin. The simple components obtained from lignin alcoholysis included phenolic ether, aromatic acids, aliphatic ether, unsaturated ketone and alcohols, etc. Condensation reaction was also observed during alcoholysis.