A spectrophotometer method was used to test oxygen radicals produced by a system of ammonium persulphate and tetramethylethylenediamine(AP-TEMED).The reaction of hydroxylamine and O-·2 produced NO-2 and then developed by sulphanilic acid and α-naphthylamine.The results indicated that there was a special absorption at 530 nm when the sample was tested by spectrophotometer, and its color responsiveness showed a quantitative relation to O-·2.Otherwise, ascorbic acid as a matter deleted oxygen radicals had a significantly quantitative relation too.