Both　synthesis　and　DFT　calculation　of　[3　+　2]　cycloaddition　reaction　(32CA)　of　quinolone-5,8-dione　with　1,3dipole　CF3CHN2　are　studied.　The　focus　of　this　work　is　to　study　the　orbital　interactions　of　this　reaction　by　using　molecular　orbital　tracing　(MOT)　method.　MOT　result　shows　that　both　quinolone-5,8-dione　and　CF3CHN2　use　three　electrons　occupied　molecular　orbitals　(MOs)　to　interact　with　each　other,　and　the　evolutive　courses　of　the　six　molecular　orbitals　of　reactants　(initial　MOs)　to　six　electrons　occupied　molecular　orbitals　of　product　(final　MOs)　are　given　in　this　work.　Three　of　the　six　initial　MOs　can　evolve　as　final　MOs　directly,　but　rest　of　them　need　to　go　through　media　orbitals　to　complete　the　evolution.　Perhaps　the　role　of　the　media　orbitals　is　to　enable　the　reaction　to　proceed　concertedly.　APT　charges　analysis　and　changes　of　bond　lengths　during　the　reaction　are　also　afforded　in　this　work,　and　the　result　shows　that　the　reaction　begins　with　a　nucleophilic　attack　of　CF3CHN2　on　quinolone-5,8-dione.　Accompanying　with　the　attack,　negative　charge　transfers　from　CF3CHN2　to　a　carbon　atom　of　quinolone-5,8-dione,　then　the　carbon　atom　attacks　nitrogen　atom　of　CF3CHN2　to　complete　the　cycloaddition.　At　last,　a　mechanism　and　a　diagram　of　the　molecular　orbital　interactions　of　the　reaction　are　given.