In view of the environmental hazards caused by SO2, the development of efficient SO2 capture technology has important practical significance. In this work, a low‐viscosity protic ionic liquids containing imidazole (Im), ether linkage, and tertiary amine structure was synthesized by acid–base neutralization of tris(3,6‐dioxaheptyl)amine (TMEA) and Im for SO2 absorption. The results showed that the solubility of SO2 in [TMEA][Im] reached 12.754 mol kg−1 at 298.2 K and 1 bar and the ideal selectivity of SO2/CO2 (1/1) is 141.7 at 1 bar. Furthermore, [TMEA][Im] can be reused and the SO2 absorption performance was not significantly reduced after five cycles. In addition, the absorption of low‐concentration SO2 (2000 ppm) in [TMEA][Im] was also tested. Further spectroscopic research and thermodynamic analysis suggested that the high SO2 uptake by [TMEA][Im] was caused by the synergistic effect of physical and chemical absorption.