The　coordination　process　and　structure　between　amidoxime　modified　polyacrylonitrile　(AO-PAN)　fiber　and　FeCl3　in　aqueous　solution　were　studied　by　using　X-ray　photoelectron　spectroscopy　(XPS),　Fourier　transform　infrared　spectrometer　(FTIR),　dynamic　thermal　mechanical　analyzer　(DTMA),　and　electrical　conductivity　method,　respectively.　The　coordination　Fe-AO-PAN　fiber　was　obtained,　and　then　used　as　a　heterogeneous　Fenton　catalyst　for　the　oxidative　degradation　of　two　azo　dyes　including　C.I.　Reactive　Red　195(RR　195)　and　C.I.　Acid　Black　234(AB　234)　in　the　presence　of　H2O2.　The　catalytic　function　of　Fe-AO-PAN　on　dye　degradation　was　investigated　with　respect　to　decoloration　percentage　in　this　work.　The　results　indicated　that　the　Fe　3+　ion　of　Fe-AO-PAN　was　coordinated　with　three　amino　nitrogen　atoms　and　three　hydroxyl　oxygen　atoms　of　three　amidoxime　units　on　the　surface　of　AO-PAN　by　covalent　bond,　and　the　coordination　number　was　six.　Moreover,　the　oxidative　degradation　of　two　azo　dyes　in　water　was　significantly　accelerated　in　the　presence　of　Fe-AO-PAN　under　light　irradiation,　and　the　azo　linkages　and　aromatic　ring　of　azo　dye　molecules　were　decomposed.　Increasing　the　degree　of　conversion　from　nitrile　group　to　amidoxime　group　on　the　surface　of　PAN　fiber　caused　not　only　higher　Fe3+　content　of　Fe-AO-PAN,　but　also　its　stronger　catalytic　performance　on　dye　degradation　in　aqueous　solution.　©　Editorial　office　of　Acta　Physico-Chimica　Sinica.