Solvent liquefaction process is one of the promising techniques for the effective utilization of waste woody biomass. In the liquefaction process, waste woody biomass such as waste bamboo could be converted to liquid reactive materials for developing biomass-based materials since waste bamboo has an advantage of providing the liquefi ed products with a small range of variances. The components of liquefi ed waste bamboo released during the liquefaction reaction with the polyethylene glycol 400 (PEG 400) solvent is highly acidic in the presence of mineral acid catalysts. Therefore, this study was carried out for analyzing the behavior of the liquefi ed residues (LRs) from waste bamboo during the solvent liquefaction process. The LRs produced during the liquefaction process were measured and related to different liquefi ed conditions. The change in the morphological surface of the liquefi ed waste bamboo samples was observed by a scanning electron microscope. The chemical changes in the functional groups were analyzed by a Fourier transform infrared spectrometer. The crystalline structure of liquefi ed waste bamboo samples was determined by X-ray diffraction. The chemical composition analysis and particle size distribution of liquefi ed waste bamboo samples were also carried out to confi rm the results. It was found that the effi ciency of liquefaction process can be improved by increasing the temperature and the amount of acid catalysts, although condensation reaction occurred under the liquefaction condition with high temperature. The liquefaction period of lignin was signifi cantly shorter than one of cellulose in the solvent liquefaction process with PEG 400. Moreover, it is indicated that the progress of liquefaction process may be prevented by smaller particle sizes of cellulose collected in liquefi ed bamboo.