To　find　out　the　impact　of　different　saturation　filling　in　the　treatment　process　of　bioretention　systems,　composition　and　dynamics　of　dissolved　organic　matter　in　runoff　were　analyzed　using　three-dimensional　excitation　emission　matrix　fluorescence　spectroscopy　(EEM).　The　results　indicated　that　the　major　organic　compounds　of　interstitial　water　were　microbial　metabolites　from　sponge　iron,　fulvic-like　substances　from　brick　bat　and　volcanic,　and　aromatic　protein-like　substances,　fulvic-like　substances　and　biometabolism　from　chippings.　After　48　h　treatment,　fluorescence　peakof　interstitial　water　associated　with　fulvic-like　and　brick　bat　were　weakened,　but　volcanic　and　chippings　were　strengthened.　The　best　purification　of　organic　substance　was　obtained　by　sponge　iron　at　84.　52%,　followed　by　volcanic　and　brick　bat　at　77.　25%　and　77.　90%　respectively,　and　chippings　at　29.　20%.　Thevolume　fluorescence　integral　of　fulvic-like　substances　in　effluent　of　bioretention　decreased　to　58.　04%　on　average,　but　aromatic　protein-like　substances　increased　on　average　to　65.　36%.　HIX　of　all　samples　were　smaller　than　4,　which　means　the　organic　compounds　mainly　come　from　microorganism　supersession　activity.　Aromatic　protein-like　substances　degraded　by　microbes　easily,　which　could　promote　microorganism　activity　and　nitrogen　removal　by　denitrification.　The　design　suggests　that　sponge　iron　and　brick　bat　would　be　better　as　the　saturation　filling.　External　carbon　source　would　be　able　to　choose　organic　compounds　which　are　easily　utilized　by　microbe.