Abstract: A considerable amount of by-product from cotton seed hulls are produced in cotton-producing areas of China which is of great developmental potential resource. Researches of cotton seed shell were introduced and methods of extraction and separation of lignin were summarized in this paper. The extraction method was: after hemicelluloses of cotton seed shell was separated, preparation of lignin using high boiling solvent was studied. The results showed that the optimum conditions were: reaction temperature was at 215℃, ethylene glycol concentration was 80%; reaction time was 2h, and ratio of material to liquid was 1∶ 8; the yield of lignin was 18. 64%; the high boiling solvent( HBS) could be recycled.