Different kinds of deep eutectic solvents were synthesized with different quaternary ammonium salts, methyl tributyl ammonium chloride, tetramethylammonium chloride, benzyl triethyl ammonium chloride and choline chloride, and DL-lactic acid with molar ratio of 1:9, respectively, and used to dissolve the lignin in eucalyptus. It was found that deep eutectic solvents of benzyl triethyl ammonium chloride/DL-lactic acid (TEBA/HL) had best solubility selectivity, as the dissolution ratio of lignin was 92.3wt% after 10 h under 90 ℃ and the dissolution ratio of total cellulose was only 8.3wt%, meanwhile, the specific value (K) of solubility selectivity coefficient between lignin and total cellulose reached to 158.5, suggesting the best solubility selectivity for lignin of TEBA/HL. FT-IR spectrum analysis showed that the structure of the extraction materials contained characteristic functional groups of lignin, and GPC analysis suggested that the molecular weights of the extraction materials were all reduced. CP/MAS 13C NMR analysis suggested that structure characteristics of the extraction materials from TEBA/HL at 90 ℃ were close to lignin of hardwoods.