A highly sensitive fluorescence quenching method for the determination of iron（Ⅲ）based on the system of iron（Ⅲ）-enoxacin-SDS has been developed.In NaAc-HAc medium,iron（Ⅲ）reacted with enoxacin and SDS to form a non-fluorescent mixed complex and quenches the fluorescence intensity of enoxacin.The experimental conditions that influence the fluorescent intensity were investigated and optimized.Under the optimum conditions the detection limit is 8.0×10-9mol/L.The linear range is 2.0×10-8-8.0×10-6mol/L.This method has been applied to the determination of trace iron（Ⅲ）in water and food samples with satisfactory results.
