Functionalized ionic liquids are receiving increasing attention in the field of flue gas desulfurization due to its unique physical and chemical properties. Research progress on the field of SO₂ removal by ionic liquids (ILs) including guanidinium-based, amines-based and ether-based ILs is summarized. Industrial application of polymerization ILs and loaded ILs to desulfurization is reviewed. Relevant suggestions on industrial application of ionic liquids based on fundamental research are put forward. The first thing is to develop functional ionic liquid for desulfurization，and thus investigate and propose its desulfurization mechanism and model; the second is to carry out the research work on immobilized ionic liquid, and explore its recycling properties, thus prolonging its service life.