Methods　for　the　conversion　of　carbohydrates　into　5-hydroxymethylfurfural　(5-HMF),　which　is　an　important　platform　chemical,　have　been　attracted　extensive　attention.　In　present　study,　Sn　modified　ionic　liquid　polymer　(PIL-Sn)　was　prepared　by　one-pot　polymerization　of　imidazole　and　epichlorohydrin,　and　utilized　as　a　novel　and　efficient　catalyst　for　5-HMF　production.　The　optimal　5-HMF　yield　of　51.1%　with　99%　conversion　was　obtained　from　glucose　catalyzed　by　PIL-Sn　in　dimethyl　sulfoxide　at　130　degrees　C　with　reaction　time　of　1　h.　This　catalytic　system　can　also　be　applied　for　the　transformation　of　other　carbohydrates　with　satisfactory　yields.　The　mechanism　of　PIL-Sn-catalyzed　conversion　of　glucose　to　5-HMF　has　been　studied　using　density　functional　theory　(DFT)　calculations.　The　DFT　results　showed　that　the　five-coordinated　SnCl5-　as　a　preferred　species　played　an　important　role　in　the　isomerization　of　glucose　to　fructose.　This　research　provides　a　new　strategy　to　design　efficient　catalysts　for　5-HMF　synthesis.