Abstract: It was observed that the oxidative color-fading reaction of CPAⅢ with potassium bromate was catalyzed by the presence of trace amounts of Sn(Ⅳ) in dil.H2SO4 medium.Linear relationship between the magnitude of the decrease in absorbance intensity at 530 nm and the concentration of Sn(Ⅳ) was found in the range of 0.0-8.0 μg·L-1,with a detection limit 0.25 μg·L-1.Based on these facts,a photometric method for the determination of trace amounts of Sn(Ⅳ) was proposed.For enrichment of traces of Sn(Ⅳ) from some complex samples,separation by the adsorption of Sn(Ⅳ) on mercapto-dextran gel was used.The proposed method has been used in the determination of traces of Sn(Ⅳ) in sample of ores,river water and human hair,giving values of RSD′s less than 9.0%,and values of recovery in the range from 96.0% to 103.0%.In the analysis of 3 CRM′s of rocks,the results obtained were in consistency with the certified values.