Recently, the radical ring-opening polymerization of cyclic monomers has become one of the most important topics because it can impart degradability to vinyl polymers by introducing functional groups and heteroatoms into the main chain through copolymerization with vinyl monomers. In this study, we investigated the possibility of the ring-opening polymerization of the cyclic sulfone compounds, including sulfolane and sulfolene derivatives. First, the reactions of 2,5-dimethyl-3-sulfolene (DMS) were predicted using density functional theory (DFT) calculations, and the reaction product was actually examined after heating in the presence of a radical initiator. Next, we synthesized and polymerized 2-vinylsulfolane (2VS), which has been reported to undergo radical ring-opening polymerization in the literature and tried to modify the resulting polymers containing the unsaturated groups in the main chain via post-polymerization reaction by ene-thiol additions. We also examined the decomposition behavior of the polymer of 2VS before and after hydrogenation. Furthermore, we discussed the reactivity of 3-exomethylenesulfolane (3EMS), which is expected to exhibit radical ring-opening polymerization similar to 2VS, as well as the structure and reactivity of the corresponding polymer.