A novel ionic polymer, poly(1,1,3,3-tetramethylguanidine acrylate) (PTMGA), was synthesized, and its SO2 absorption and desorption properties were studied for the first time. 1,1,3,3-Tetramethylguanidine acrylate, a polymerizable ionic liquid (IL), was first prepared via neutralization of 1,1,3,3-tetramethylguanidine and acrylic acid. PTMGA was then synthesized via free radical polymerization of TMGA. The polymer adsorbed SO2 with high selectivity, capacity, and rate. The absorption capacity and rate of PTMGA were significantly higher than the monomer. The SO2 absorbed at a relatively low temperature was effectively desorbed at higher temperatures and/or under vacuum. The absorption/desorption process could be repeatedly operated, and thus the polymer was reused. Under a typical operation condition, about 0.3 g of SO2 per gram of polymer was separated in each cycle. The PTMGA material showed a good potential as solid-state SO2 absorbent for applications in purification of SO2-containing gas such as fuel gas desulfurization.