Abstract: A series of Pt/ZrO₂ and Lewis acid co-catalytic systems, such as Pt/ZrO₂-FeCl₃, Pt/ZrO₂-CuCl₂ and Pt/ZrO₂-NiCl₂, were prepared for selective depolymerization of alkali lignin to generate oligomers with high content of phenolic hydroxyl groups and low content of solid residue. The effects of reaction parameters such as the component and dosage of catalysts, hydrogen pressure, reaction temperature and reaction time on the reductive depolymerization of alkali lignin were investigated. GPC, FT-IR, ³¹P NMR, ¹³C NMR and 2D-HSQC NMR were conducted to reveal the changes of structure and linkage in alkali lignin and its depolymerized products. The results showed that the synergetic catalysis of Pt/ZrO₂ and Lewis acid(FeCl₃, CuCl₂, NiCl₂) exhibited higher catalytic activity and better selectivity for phenolic compounds than Pt/ZrO₂. Pt/ZrO₂-FeCl₃ exhibited the best catalytic activity among Pt/ZrO₂-FeCl₃, Pt/ZrO₂-CuCl₂ and Pt/ZrO₂-NiCl₂. Under the optimal conditions of mass ratio of Pt/ZrO₂-FeCl₃ to lignin 1:15, mass ratio of FeCl₃ to Pt/ZrO₂ 0.2, reaction temperature 300 ℃, reaction time 3 h, hydrogen pressure 4 MPa, the given products with higher content of phenolic hydroxyl groups(362 mg/g) and lower content of solid residue(2.70%) were obtained, as well as, the conversion rate of lignin and the number average molecular mass(M_n) of the product were 89.0% and 998, respectively. Furthermore, the comparative structure characterization of the alkali lignin, Pt/ZrO₂ catalytic depolymerization product(DL1) and Pt/ZrO₂-FeCl₃ catalytic depolymerization product(DL2) demonstrated that S units were more prone to be damaged during the reductive depolymerization of alkali lignin, the cleavage of methoxy groups and intramolecular β-O-4 and β-β linkages were more effective facilitated by Pt/ZrO₂-FeCl₃ than Pt/ZrO₂.