A new resonance light quenching method for the determination of selenium has been established.In presence of polyvinyl alcohol,ammonium molybdate can react with cetylpyridimium bromide to form an ion-association complex in Na2B4O7-NaOH buffer solution at pH 10.6,which can produce strong and stable resonance light scattering.The chemical 1-(2-pyridylazo)-2-naphthol can promote the disassociation of the ion-association complex to cause the resonance light quenching.In addition,selenium can accelerate the quenching.Through single factor experiments and orthogonal designed experiments L16(45),the optimum reaction conditions were determined.Good linear relationship between resonance light quenching intensity and Se(Ⅳ) concentration occurs in the content range of 0.8~4.8 μg/L with the maximum resonance light quenching wavelength at 375 nm.The method has been applied in the determination of selenium in selenium fortified salt and healthy balanced salt.The results showed well consisted with those obtained by fluorescence method.The relative standard deviation was 1.07 %~1.61 %(n = 5),and the average recovery was 99.5 %~101.5 %.