In this work, four novel PEG-linked dicationic ionic liquids (DILs) with one kind of thiocyanate anion and chloride anion and a traditional DIL with thiocyanate anion were synthesized and used for SO2 absorption. The physicochemical properties of PEG-linked DILs with thiocyanate anion were measured. The performance of SO2 absorption by the five DILs at different pressures, temperatures, and water contents was also investigated. The results showed that the absorption process was fast and the absorption capacities of the DILs were much higher than those of monocationic ILs; especially, [E(3)Eim(2)][Cl](2) had the absorption capacity up to 6.779 mol SO2 /mol IL at 20 degrees C and 1 bar. The mechanism of SO2 absorption by DILs was also studied with FT-IR and NMR, which revealed there just existed physical interaction between DILs and SO2. PEG-linked DILs have a high selectivity between SO2 and CO2. Meanwhile, the good absorption performance of PEG-linked DILs could be maintained after five successive absorption/desorption cycles, implying these ILs show great potential as candidate absorbents for SO2 absorption.