With the decline in the availability of petrochemical resources, lignocellulosic biomass as a renewable resource has been getting more and more attention. The atmospheric liquefaction technology has been used widely, which is one of the effective ways of biomass components utilization. In this paper, to optimize the liquefaction conditions, a single-factor method was used to study the effects of liquefaction temperature, mixing ratio of a compound liquefying agent, liquid-solid ratio, catalyst dosage and reaction time on the liquefaction yield of corn stalk. The thermo-gravimetric analyzer (TGA), gas chromatography and mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectra were adopted to detect the volatile degradability and components of the biofuel. The results indicated that the optimum conditions were determined as liquefaction temperature 170 ℃, diethylene glycol (DEG)/1,2-propanediol (PG)=1:2, a liquid to solid ratio of 5:1, phosphoric acid dosage 10% and reaction time 45 min. Under this condition, the liquefaction yield was up to 99.50%. The results of TGA showed that the biofuel contained more than 80% of compounds with a carbon number less than 25, and the final carbon content after pyrolysis was about 15%. GC-MS presented that 39 kinds of organic compounds were tested in biofuel, among which alcohols were the most, phenols were the second, and their relative contents were 70.70% and 25.63%, respectively. There were also some organic acids (2.80%), ethers (0.64%), esters (0.10%) and ketones (0.13%). Its components were complicated, and high oxygen content, so its stability was limited. ¹H- and ¹³C-NMR explained that different chemical shifts δ corresponded to different types of protons and carbon atoms. The distribution of hydrogen and carbon in the biofuel was clarified, conducive to the further exploration of its molecular structure. Hence, theoretical foundation and technical support could be provided for the existing related liquefaction technology and then promote the efficient utilization of biomass resources and the development of biomass-based products.