Abstract: An ionic liquid 1- methyl-3-butyl imidazolium chloride ［BMIM］Cl was synthesized through nucleophilic substitution reaction using N-methyl imidazolium and chlorobutane, and its molecular structure was confirmed by methods such as FT-IR、¹³C-NMR、 UV、MS. Effects of extraction time, temperature, sulfur compounds (T, BT or DBT) and volume ratio were presented using single factor analysis to discuss impacts on extractive desulfurization ability. In the single-stage extractive desulfurization process, removal of DBT in n-octane using ［BMIM］Cl was 56.2% with volume ratio of 1∶1, in 30 min at 40 ℃ under mild reaction conditions. Also, multistage extraction and extractive-oxidative desulfurization process was studied：In the 4-levels consecutive extractive desulfurization, removal of DBT in n-octane using ［BMIM］Cl could reach 97.6% under similar reaction condition; All sulfur compounds (T, BT or DBT) could be removed more than 85%