In the presence of Triton X 100 at pH 13 the reaction between silver (Ag+) and chromogenic reagent, 2,4-dibromo-6-carboxy-benzenediazoaminoazo-benzene (DBCBAA) was developed to form a red complex. This reaction was highly selective in the presence of disodium ethylene diamine tetracetate (Na(2)EDTA). Because of the interference of excess of DBCBAA the mw method named Its primary-secondary wavelength spectrophotometry (PSWS) was applied instead of the ordinary spectrophotometry for the determination of trace amounts of silver in wastewater Results showed that such a method gave out the better precision and higher accuracy thm the ordinary method By analyzing several wastewater samples, the relative standard deviations were less than 3.69% and the recovery rate of Ag between 93.5 and 104%.