With concentrated phosphoric acid as catalyst and various organic solvents as liquefying agents, corn stalk powder was liquefied into bio-oil in an autoclave, under the condition of 170 ℃. Analysis was conducted to throw light on the liquefying effects of three different agents; they are glycerol triacetate with ethylene carbonate, glycerol with ethylene carbonate and polyethylene glycol with ethylene carbonate(6∶1 ω/ω), and the properties of the biomass liquefaction oil products. FT-IR was applied to examine raw material and residues, whose chemical compositions were further analyzed with the use of GC-MS. The results of experiments indicated that the liquefaction yield of polyethylene glycol was 97.84%, the yield of glycerol triacetate was 80.20%, the yield of glycerol were36.97%. FT-IR analysis showed that the functional groups of cellulose, hemicelluloses and lignin was disappeared and liquefaction is best when polyethylene glycol with ethylene carbonate was used as the liquefaction agent. GC-MS analysis showed that the oil composition produced in this way is complex, contains organic acids and ketones, alcohols and ethers, aromatic, sugars and esters compounds.