The　interactions　between　carboxymethylchitosan　and　alkyltrimethylammoniumbromides　were　studied　in　aqueous　solution.　The　dependences　of　aggregation　behavior　on　surfactant　concentration,　polyelectrolyte　concentration,　as　well　as　surfactant　chain　length　were　investigated　mainly　using　fluorescence　spectroscopy　method.　The　variation　of　I-1/I-3　of　pyrene　fully　characterized　the　aggregation　behavior　of　the　polymer-surfactant　complex.　Meanwhile,　based　on　that　Nile　red　has　the　sensitivity　to　the　environmental　polarity　different　to　pyrene,　the　changes　of　aggregates　size　and　number　can　be　reflected　by　the　fluorescence　spectroscopy　of　Nile　red.