Polymer-supported selenium has been reported as a heterogeneous catalyst that is easily separated from the reaction system, thereby making the recovery and reuse of the catalyst more convenient. However, the utilization of polymer-supported selenium in the preparation of catalysts is not restricted to the aforementioned technical advantages. Recent studies have shown that polymer-supported selenium and small-molecule organoselenium catalysts have significant performance differences, leading to distinct reaction mechanisms, which offer more opportunities for the development of new organic reactions.