Abstract: An environment friendly ionic liquid (IL) 1-methyl-3-butyl imidazoliumtetrafluroborate ([BMIM]BF4) was synthesized by green synthesis method. The investigations of preparation method and the extractive desulfurization performance were conducted. The intermediate product [BMIM]Cl was obtained firstly by nucleophilic substitution reaction of N-methyl imidazolium and 1-chlorobutane under solvent-free condition, and then the product reacts with NaBF4 to get the target product ([BMIM]BF4). The molecular structure was confirmed by characterization of UV、FT-IR、MS and13C-NMR. The effect of extraction time, extraction temperature, sulfur compound type (BT or DBT), ratio of IL to model oil on extractive desulfurization was presented. The multistage extraction of DBT model oil with IL [BMIM] BF4 and its regeneration were studied. The results indicate that at the conditions of extraction temperature 40 ℃, 30min, and IL to oil volume ratio 1:2, the extraction desulfurization rate is 54.4% in single stage. While by 3 stage extractions, the sulfur removal rate is up to 90% and the IL can be recycled.