Abstract: Lignin-based epoxy resin is synthesized by a phenolated lignosulfonate,which comes from sodium lignosulfonate through phenolated reaction with HBr and tributhexadecylphosphonium bromide as catalysts.The phenolated lignosulfonate is epoxidized by epichlorohydrin to produce lignin-based epoxy resin.The components and structure of phenolated product are characterized by the elemental analysis,Gel permeation chromatography (GPC),Fourier transform infrared spectrometer (FT-IR),ultraviolet-visible spectrometry (UV),and ¹H-nuclear magnetic resonance (¹H-NMR).Results show that parts of the methyloxygen group of sodium lignosulfonate are transformed into phenolic hydroxy,and the content of the phenolic hydroxy group of phenolic products increases 2.6 times than that of sodium lignosulfonate,which satisfies the requirement of prepared lignin-based epoxy resin.