<p>Biomass energy occupies an important position in the future energy structure because of its renewability, environmental friendliness, and abundant reserves. However, achieving its efficient liquefaction as well as the quality improvement of the liquefaction products is still a major challenge. In this study, a supported hydrogenation catalyst was introduced to couple the hydrogen supply liquefaction with catalytic liquefaction process. Firstly, wood chips were used as the raw material, with ethanol as the solvent. The study investigated the effects of catalyst composition and other conditions on biomass liquefaction yield and product quality, identifying the most effective catalyst system. The catalyst structure was characterized using various techniques. The experimental results showed that the optimized catalyst systems Ni-Co/AC and Ni-Ag/γ-Al₂O₃ could reach 57% and 51%, respectively, with the two materials of activated carbon (AC) and γ-Al₂O₃ as the catalyst carriers, Ni as the active component, and the co-catalysts loaded with 2.5% Co and 2% Ag, respectively. The compositional distribution of the liquefaction products was analyzed by gas chromatography–mass spectrometry, and the effects of the synergistic action of hydrogen donor and catalyst on the reaction pattern of biomass liquefaction were preliminarily investigated, and a possible mechanism was proposed. It was analyzed that the catalyst could induce the hydrogen donor to continuously produce active hydrogen to combine with the free radicals generated from biomass liquefaction, which could promote the chain breaking of macromolecular compounds, reduce the condensation coking, and improve the yield. This study not only provides experimental evidence for the optimization of catalyst systems but also offers a new theoretical perspective for investigating the synergistic mechanism between hydrogen donors and catalysts. It provides important scientific support for the efficient utilization of biomass and the upgrading of bio-oils.</p>