It is a significant technique for choosing proper solvents during liquefaction of biomass process to produce fuel additives and valuable chemicals. In this study, the mixtures of new low-cost diethylene glycol (DEG) with 1,2-Propanediol (PG) and the traditional ethylene glycol (EG) with PG (6∶1 ω/ω) were adopted as liquefying agents. And analyses were conducted to throw light on the effects of these two different liquefying agents on the liquefaction yield and the properties of the biomass liquefaction oil products. The properties of the corn stalk, bio-oil and residue were studied with gas chromatography and mass spectrometry (GC-MS), Fourier transform infrared spectroscopy (FTIR), pyrolysis-gas chromatrography/mass spectrometry (Py-GC/MS) and X-rays diffraction (XRD). The results indicated that when the DEG and PG were cooperatively used as liquefying agent, the liquefaction yield was 98.57%. And there was a liquefaction yield of 96.08%, with the mixture of EG and PG as liquefying agent. GC-MS analysis results showed that the main components of bio oils were alcohols and organic acids, with a total content of more than 97%. However, the bio oil obtained by EG mixed PG liquefaction contained nearly 60% of organic acids, which was the main cause of the acidity and corrosiveness of the bio oil, and was not conducive to the liquefaction. The characteristic absorption peaks of the corresponding functional groups of some oligomers in the bio oil were detected by FTIR to compensate for the limitation of the GC-MS characterization. It turned out that many active chemical bonds were generated in the liquefaction system, leading to improving the activity of the reaction system, and the bio oil contained a large number of C—O and CO functional groups, which strongly supported the results of the conclusions of GC-MS. Furthermore, Py-GC/MS, FTIR and XRD were applied for the characterization of the liquefaction residues. Py-GC/MS explained that the liquefaction residue composition produced in this way was complicated and contained a certain amount of large molecular substances which were very difficult to degrade. The liquefaction residues were mainly originated from the polycondensates or derivatives of interactions between small molecules of lignin or hemicellulose degradation or unreacted cellulose, and the macromolecular substances generated by the reaction of the degradation products of three components and liquefying agents. The signals of FTIR reported that the functional groups of cellulose, hemicellulose and lignin were disappeared and the liquefaction degree of lignin was the largest. Results from XRD presented that because of the destruction of crystalline structure of carbohydrates, the cellulose molecules was cracked, indicating that the cellulose was degraded and the degree of liquefaction was high. Consequently, all the results successfully confirmed that the liquefaction effect of DEG mixed PG was better than the mixture of EG and PG. Even it provided an efficient and environmental process for generating bio-oil from lignocellulosic mass at a low cost in liquefaction of corn stalk.