With the fulfillment of China’s potato staple food strategy, potato stem leaves gradually become plentiful lignocellulosic biomass resources. However, its cell wall has high-crystalline structure and available surface area which were difficult to hydrolyze and produce biogas by microorganism. Therefore, the effect of lignocellulosic composition, structural and anaerobic digestion from the pretreated potato stem leaf by ionic liquids and dimethyl sulfoxide was evaluated. The potato stem leaf was pretreated with ionic liquids 1-N-butyl-3-methyimidazolium chloride ([C4mim]Cl), 1-ethyl-3-methlyimidazolium acetate ([C2mim]Ac) and dimethyl sulfoxide (DMSO) under the condition of 130℃ for 120min. Compared with untreated group (19.8% lignin content), the composition and structure of lignocellulosic from the regenerated potato stem leaf was changed and the lignin content was reduced by 31.8%～43.9%. The dissolving capability of the solvents followed the order: [C2mim]Ac, [C2mim]Ac/DMSO, [C4mim]Cl/DMSO, DMSO, [C4mim]Cl. The anaerobic digestion data demonstrated the lag phase of anaerobic digestion start-up period was shortened by 9d. Because the solubility of cellulose was risen with the increase of the H-bonds accepting ability of the anions which would form more efficient H-bonds between the hydroxyl protons of cellulose and the anion, meanwhile, the crystalline structure of cellulose became lower and the surface became more porous. In other words, the hydrolytic acidification stage was almost accomplished after pretreatment. Plenty of the small molecular substances, which were easy to be used by methanogens, were dissolved out. The cumulative biogas production and the highest methane content were increased by 3.2%~76.3% and 14.3%~25.1%, respectively, compared with untreated potato stem leaf. The cumulative biogas production and the highest methane content of each pretreated groups were 7.21L and 69.2% ([C4mim]Cl/DMSO), 5.12L and 64.5% ([C2mim]Ac/DMSO), 5.07L and 65.7% ([C2mim]Ac), 4.35L and 64.3% ([C4mim]Cl), 4.22L and 63.2% (DMSO), respectively. The ionic liquids were almost completely recovered by aqueous biphasic systems (ABSs) with tripotassium phosphate (K3PO4), the recovery rates of DMSO, [C2mim]Ac and [C4mim]Cl were 95.1%, 91.8% and 89.6%, respectively. There were still many issues in putting ionic liquids into practical applications, including the high cost of ILs, regeneration systems and requirements and mechanism of inhibitor generation. Further research was urgently required to dispose such challenges.