The extractive removal of sulfur compounds (S-compounds) from Dongying and Liaohe diesel fuels with [BF4](-)-based ionic liquids were systematically investigated. The results show that the absorption capacity of an ionic liquid for the S-compounds in diesel fuels relies on its structure and its size. In the case of the two examined diesel fuels, both elongating the cation tail length and increasing the mass ratio of ionic liquid/diesel fuel promote the desulfurization ability of the examined ionic liquids. The results also show that imidazolium-based ionic liquids display higher extraction efficiencies than pyridinium-based ionic liquids, presumably owing to the fact that the rings of the S-compounds are similar to the imidazolium head ring. With the I : I mass ratio of ionic liquid/diesel fuel. the rates of the first desulfurization of Dongying and Liaohe diesel fuels using [C(8)mim][BF4] amount to 29.96% and 39.76%. suggesting that [C(8)mim][BF4] is a promising extractant for desulfurization of these diesel fuels.