A　water-soluble　derivative　of　chitosan,　carboxymethylchitosan　(CMCH),　was　mixed　with　alkyltrimethylammoniumbromides　(CmTAB)　and　was　studied　on　the　adsorption　at　air/water　interface　using　equilibrium　and　dynamic　surface　tension　method.　The　effects　of　surfactant　and　polymer　concentrations,　surfactant　chain　length,　as　well　as　pH　of　solution　were　investigated.　Addition　of　the　surfactants　remarkably　promotes　the　polymer　adsorption.　Increasing　any　one　of　surfactant　concentration,　surfactant　chain　length,　and　pH　will　facilitate　the　adsorption　of　the　mixture　whereas　little　effects　of　polymer　concentration　were　observed.　The　results　are　explained　in　terms　of　the　interaction　between　CMCH　and　CmTAB　under　different　conditions.