Ionic liquids (ILs) as promising absorbents for SO2 capture in flue gas desulfurization have been extensively studied. In this work, a multisite absorption strategy was used to synthesize ether-linked diamine protic ionic liquids (EDPILs) for efficient SO2 capture. The prepared EDPILs containing ether-linkage chain exhibited superior SO2 absorption relative to conventional protic ionic liquids (PILs). Density functional theory calculations demonstrated that the ether-linkage chain intensified the physical interaction between EDPILs and SO2. In a subsequent experiment, bis(2-dimethylaminoethyl) ether dilactate [BDMAEE][L](2), which possessed outstanding SO2 capture capacities, was used to prepare aqueous solutions (aq), which reduced viscosity of PILs and improved their applicability. An in-depth assessment of the desulfurization performance of [BDMAEE][L](2) aq revealed that effective SO2 absorption can be achieved even at relatively low concentrations. Specifically, 50 wt % [BDMAEE][L](2) aq exhibited a high absorption capacity (1.04 mol(SO2)/mol(ILs), 0.097 g(SO2)/g(absorbents)) as well as a high SO2/CO2 selectivity at 0.2 vol % SO2 and 40 degrees C. Overall, ether-linked absorbents with improved desulfurization performance (high SO2 absorption capacity, satisfactory SO2 removal efficiency, and excellent reusability) possess good application prospects in flue gas desulfurization.