Abstract: The catalytic performance of four keggin-type polyoxometalates with different oxidability to degrade lignin into phenolic compounds in H₂O₂ system was compared. H₃PWO₄₀ and H₅PMo₁₀O₄₀ catalysts had good effect on the depolymerization of lignin. Under the conditions of 140 ℃, 1 mL H₂O₂, 1 h, the yield of bio-oil could reach 54.60% by using H₃PWO₄₀ as catalyst, and the total yield of phenolic compounds could reach 6.38%. By using H₅PMo₁₀VO₄₀ as catalyst, the yield of bio-oil could reach 60.96% and the total yield of monophenol compounds could reach 11.67% at 140 ℃, 2 mL H₂O₂ and 1 h. Compared with HPW, PMo₁₀O₂ system due to its strong oxidizing ability. A series of characterizations such as FT-IR, 2D-HSQC, and GC-MS were performed to prove the effectiveness of the system in depolymerizing lignin into phenolic compounds.