Environmental concerns have driven the need to remove sulfur-containing compounds from fuel. The removal of sulfur compounds from fuel (gas oil) with [BMIM][FeCl₄] based ionic liquids as catalyst were systematically investigated. The results show that the absorption capacity of an ionic liquid for the sulfur compounds in gas oil relies on its structure and its size. In the case of the examined gas oil, both the cation tail length and the time adsorbed ionic liquid with gas oil promote the desulfurization ability of the examined ionic liquids. The results also show that imidazolium-based ionic liquid have high extraction efficiencies, presumably owing to the fact that the rings of the sulfur compounds are similar to the imidazolium head ring. With the 1: 5 mass ratio of ionic liquid / gas oil, the rates of the desulfurization of gas oil reach 80.0, 88.5 % within the first 60 and 90 min respectively. It is found [BMIM][FeCl₄] based ionic liquids has the best effect on the selective removal of sulfur-containing compounds from gas oil at room temperature. Moreover the results show that the kinetics of desulfurization of gas oil can be described well with the first-order equation.