Aqueous ZnS∶Mn quantum dots（ZnS∶Mn QDs） capped by thioglycolic acid and emitting fluorescence of 590 nm were obtained at room temperature.Based on the fluorescence quenching of ZnS∶Mn QDs caused by sulfadiazine sodium（SDS）,a simple,rapid and specific quantitative method was developed for the determination of SDS.Experimental conditions including temperature,reaction time and pH value of buffer affecting the detection for SDS were investigated.Under the optimal conditions,the calibration plot between the intensity ratio I0F/IF and the concentration of SDS was linear in the range of 625×10-6-375×10-4 mol?L-1 with a correlation coefficient of 0998.The limit of detection(LOD)（3σ/k） was 386×10-6 mol?L-1.The method was simple and rapid,and was applied in the determination of SDS in the injection sample with average recovery of 100%.In order to study the possible interaction mechanism,the influence of salt effect on the fluorescence intensity of QDs-SDS was discussed.The result indicated that SDS could bind to the ligand of ZnS∶Mn QDs surface through electrostatic force,which resulted in fluorescence quenching.