NOVELTY - Separating ginkgolide B from ginkgolide mixture comprises preparing raw material liquid through the ginkgolide mixture and hydrophobic organic solvent; taking hydrophilic ion liquid or binary mixed solvent composed of ion liquid and water as extracting agent, taking the solvent which is the same as the raw material liquid solvent as washing agent to do fractionation; where the fractionation comprises an extracting stage and a washing stage; and concentrating the extracted liquid under vacuum, washing and drying to obtain the ginkgolide B.    USE - Separating method of ginkgolide B from ginkgolide mixture.    ADVANTAGE - The method has high separation efficiency, consumes little solvent, and is safe, environment-friendly, and easy for industrial production.    DETAILED DESCRIPTION - Separating ginkgolide B from ginkgolide mixture comprises:    (A) preparing raw material liquid through the ginkgolide mixture and hydrophobic organic solvent; taking hydrophilic ion liquid or binary mixed solvent composed of ion liquid and water as extracting agent, taking the solvent which is the same as the raw material liquid solvent as washing agent to do fractionation; where the fractionation comprises an extracting stage and a washing stage; flowing the extracting agent into the fractionation extracting system from the extracting stage, flowing the raw material flows into the fractionation extracting system from the last stage of the extracting stage, flowing the washing agent into the fractionation extracting system from the first stage of the washing section, combining the raw material liquid on the last stage of the washing stage and then leading the mixture into the extracting stage, doing multi-stage reverse extraction to the mixture through the extracting phase and washing phase, flowing the extracted liquid containing ginkgolide A and ginkgolide C out from the first stage of the washing stage, flowing the extracted liquid containing the ginkgolide B out from the first stage of the extracting stage, collecting the extracted liquid;and    (B) concentrating the extracted liquid under vacuum, washing and drying to obtain the ginkgolide B; where the hydrophobic organic solvent is ethyl acetate, butyl ethanoate, 4-8C primary alcohol or 4-8C secondary alcohol; the hydrophilic ion liquid is composed of cation M+ and anion N-; the cation M+ is one of imidazole cation with substituent group, pyridine cation with substituent group, phosphonium cation with substituent group, piperidine cation with substituent group, quaternary ammonium cation with substituent group or pyrrole cation with substituent group; the anion N- is one of chloride ion, bromine ion, iodine ion, tetrafluoroborate, trifluoroacetic acid, trifluoromethanesulfonic acid, ethanesulfonic acid, dimethyl phosphinic acid, diethyl phosphate, dihydrogen phosphate or amino acid.