Abstract: To deeply understand the catalytic mechanism of bio-char on volatiles during biomass pyrolysis, a variety of functionalized graphenes, including RGO-OH, RGO-COOH and RGO-NH₂, were used as functional-group-rich char models. The catalytic effect of these different surface functional groups on the typical lignin α-O-4 compound benzyl phenyl ether(BPE) at 400℃ was investigated by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The results showed that -OH and -COOH significantly increased the degree of thermal decomposition of BPE. The conversion of BPE increased from 0.1% (without catalyst) to 37.73% (with RGO-COOH as catalyst) and 53.78% (with RGO-OH as catalyst), respectively. However, -NH₂ only provided a BPE conversion of 12.29%, even weaker than the catalytic activity of non-functionalized reductive graphene oxide (RGO) (BPE conversion of 25.63%), indicating that the RGO as carrier also had a certain catalytic effect on BPE conversion, and -NH₂ played an inhibitory role. The decomposition of BPE was mainly caused by the sp³ C_α-O bond cleavage, and the proudcts were mainly phenol and 2-benzylphenol. The surface oxygen-containing functional groups (-OH and -COOH) promoted the dimerization reaction, forming 2-benzylphenol and 4-benzylphenol. In addition, the functional groups also could promote the cleavage of sp² C_aryl-O, and the main product was benzaldehyde.