To　obtain　a　better　understanding　of　relationship　between　structure　and　degradation　performance　of　azo　dye,　the　modified　polyacrylonitrile　(PAN)　fiber　Fe　complex　was　used　as　the　heterogeneous　Fenton　catalyst　for　the　oxidative　degradation　of　28　typical　water-soluble　anionic　azo　dyes.　The　quantitative　relationship　between　structure　and　decoloration　percentage　or　TOC　removal　of　the　dyes　was　investigated　by　using　multivariate　linear　regression　analysis.　The　QSPR　(quantitative　structure　property　relationship)　models　were　developed　and　then　applied　for　predicting　the　degradation　performance　of　similar　azo　dyes.　The　results　indicated　that　the　azo　dyes　with　different　structures　were　effectively　degraded　and　mineralized　in　the　presence　of　modified　PAN　fiber　Fe　complex.　Moreover,　there　is　a　good　linear　relationship　between　molecular　descriptors　including　MW/S　(molecular　weight　divided　by　the　number　of　sulphonate　groups),　the　number　of　azo　linkage,　the　number　of　aromatic　rings　or　inorganic/organic　value　and　decoloration　percentage　or　TOC　removal　of　the　dyes.　MW/S　and　the　number　of　azo　linkage　served　as　the　most　significant　negative　effecting　factor　for　decoloration　percentage.　While　the　number　of　azo　linkage　or　the　number　of　aromatic　ring　acted　as　the　most　significant　negative　or　positive　effecting　factor,　respectively.　The　QSPR　models　developed　are　stable　enough　to　predict　the　degradation　performance　because　the　relative　error　and　correlation　coefficients　between　the　predicted　and　the　observed　decoloration　percentage　or　TOC　removal　are　accepted.