Repeated utilization of ionic liquid to extract lipid from algal biomass is evaluated.In this work,different kinds of ionic liquids and reaction conditions of oil extraction are optimized.Microalgae cell morphological performances are compared pre-and post-treatment.Repeated use of ionic liquids in microalgae oil extraction experiments was tested.[BMIM][MeSO4] showed the best oil extraction lipid extraction efficiency and no less than 70℃ and 2.5 hours are the optimal reaction temperature and time for low cost expected.The ratios(ILs: methanol)of 1:7 and 1:4 are successful in complete extraction of the lipids from microalgae.Five times average oil extraction results of 1:7 and 1:3 are17.74%and 19.14%of cell dry weight by using recycling of [BMIM][MeSO4] –methanol co-solvent system,while a little loss of ionic liquid in every recovery process appears.It is suggested that the potential of lipid extraction in this ILs-methanol co-solvent system is promising due to the high efficiency,low cost,safety,environmental protection and other characteristics.