An　environmentally　friendly　polymer　catalyst　(PAS)　was　synthesized　via　inverse　emulsion　polymerization　using　acrylic　acid　(AA)　and　1-vinyl　imidazole　(VI)　as　monomers.　The　excellent　catalytic　activity　of　PAS　was　attributed　to　the　synergistic　effects　of　the　carboxyl　groups　(-COOH)　as　hydrogen　bond　donors　and　N-heterocyclic　carbene　(NHCs)　as　electron　donor,　as　well　as　the　swelling　properties　of　the　polymer,　which　can　enrich　the　substrate　into　the　polymer　network,　increasing　the　contact　between　the　substrate　and　active　sites.　Characterization　results　from　thermogravimetric　(TG)　analysis　and　small-angle　X-ray　scattering　(SAXS)　showed　that　the　excessive　imidazole　addition　disrupted　the　polymer＇s　chain-like　structure,　significantly　reducing　its　swelling　properties.　And,　the　catalytic　performance　is　influenced　by　both　the　amount　of　imidazole　in　PAS　and　the　swelling　properties　of　the　polymer.　Finally,　the　reaction　mechanism　of　the　CO2　cycloaddition　reaction　catalyzed　by　PAS　was　proposed　and　validated　through　density　functional　theory　(DFT)　calculations.