Researchers have been committed to transforming low-grade biomass resources, such as corn stalks, into high-value chemicals to improve their utilization value. Therefore, it is very significant to carry out the liquefaction of corn stalks in the presence of polyhydric alcohols with an acid catalyst at atmospheric pressure and study the main components, pyrolysis and fiber properties of the liquefaction residue. In this paper, the chemical groups, pyrolysis property, thermogravimetric loss, crystal structure, and microstructure of corn stalk and its liquefaction residue were analyzed by Fourier transform infrared spectroscopy (FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), thermogravimetric analysis (TGA), X-rays diffraction (XRD), and scanning electron microscopy (SEM). FTIR analysis results showed that the characteristic absorption peaks of three components (cellulose, hemicellulose and lignin) in liquefaction residue almost disappeared. It was mainly large molecules produced by interactions of some small molecules produced by the degradation of three components and incompletely degraded cellulose. Py-GC/MS showed that 89 kinds of organic compounds could be identified in pyrolysis products of liquefaction residue, including furans (10.64%), phenols (18.89%), ketones (3.73%), hydrocarbons (35.23%), alcohols (4.17%), aldehydes (4.31%), ethers (1.25%), organic acids (4.79%) and heteroatom-containing compounds (17.00%). The carbon number of these organic compounds was higher than that of similar compounds in corn stalks. TGA analyzed the thermal weight loss of liquefaction residue. In the heating phase, the rapid weightlessness phase and the slow weightlessness phase, the mass loss was about 3%, 45%, and 4%, respectively. Its pyrolysis conditions were more severe than those of corn stalks. Results from XRD revealed that the main and secondary peaks of liquefaction residue disappeared, destroyed the cellulose I latticed and formed an amorphous structure. In addition, from SEM characterization results, the liquefaction residue exhibited a disorganized, rough, irregular, and granulated morphology. In conclusion, the corn stalk’s fibrous structure was destroyed and liquefied under this liquefaction condition. The theoretical foundation and technical support could be provided for preparing wood-based carbon materials from liquefaction residue and then promoted the high value-added utilization of biomass resources.