Abstract: The liquefaction of ligno-cellulosic biomass materials of bamboo, poplar, pine and eucalyptus woods was investigated in methanol under high pressure with H₂SO₄ as catalyst. The results indicated that the biomass materials are converted into bio-gas, solid residue and bio-oil after reaction at 200 ℃ for 30 min. The bio-oil can be further separated into a variety of high value-added products such as alkyl polyglycosides, levulinate acid esters, and polyphenols. Alkyl polyglycosides is the main component of the liquefied products and accounts for 83.38% by weight; besides, phenolic products are mainly composed of 4-ethyl-2-methoxyphenol, eugenol and 3, 4-dimethoxyphenol, which account for about 65.79% by weight. Considering the molecular structure of lingo-cellulosic materials, it was proposed that cellulose and hemicellulose are transformed to alkyl glucoside, levulinate esters, etc. with methanol catalyzed by sulfuric acid under high pressure. Due to electron donating effects of phenolic hydroxyl and methoxy groups, guaiacol, phenol and a series of phenolic compounds are formed through the cleavage of C-C bond of guaiacyl units in lignin.