In this study, wheat straw (WS) was pretreated using hydrothermal technology to the co-produce xylo-oligosaccharides (XOS) and bio-based polyols, thereby enabling the efficient utilization of all components of WS. The results showed that hydrothermal pretreatment significantly reduced the hemicellulose content in WS (from 21.18% to 11.93%), with an XOS yield of 44.9%, and simultaneously increased the relative contents of cellulose and lignin in hydrothermally pretreated wheat straw (HWS). Subsequently, the liquefaction behavior of HWS was investigated using glycerol as the main liquefaction solvent and sulfuric acid as the catalyst. Hydrothermal pretreatment could disrupt the dense structure of WS, increase the exposed surface area of cellulose, and significantly enhance porosity, thereby improving liquefaction efficiency. The liquefaction effect was optimal. The liquefied residue rate (LR) of HWS was 8.17% under the optimal conditions (PEG-400 to glycerol ratio of 4:6, a reaction time of 120 min, a temperature of 170℃, a catalyst dosage of 3%, and a liquid-to-solid ratio of 5:1), and the hydroxyl value was 496 mg KOH/g, which was lower than that of WS. In addition, hydrothermal pretreatment could significantly increase glycerol concentration in the liquefaction solvent, thereby reducing liquefaction costs.