Abstract: Lignin only accounts for about 6% of total mass in tobacco stem, but it influences the harmful substances in the side stream smoke of cigarette in a significant way. Traditional researches focus only on the determination of lignin content. In the present work, we investigate four typical imidazolium-based ionic liquids for efficient extraction of lignin under mild conditions and 1-ethyl-3-methylimidazolium diethylphosphate (EmimDEP) shows the best results. The pretreatment of stem using water at 80 ℃ for 30 min can not only remove most of the sugars but also loose the microfibers. The extractive rate of lignin reaches 85.38% at 150 ℃ for 4 h and the purity of lignin is 90.21%.