Abstract: A new catalytic spectrophotometric method for the determination of race silver was stadied.It was based on the catalytic effects of Ag(Ⅰ) on the oxidation reaction between potassium persulfate and ethyl violet in the HAc-NaAc buffer and 88℃ temperature of water bath.The influential factors of reaction and the optimum conditions for the determination of silver were investigated in detail.The detection limit is 4.0 ng /mL.The linear range of determination forsilyer is 0~80 ng /mL.The apparent reaction rate is 3.96×10^-4/s and the apparent activation energy of the catalytic reaction is 40.04 kJ/moL.The method has been applied to the determination of trace silver in waster fixative with satisfactory result compared with the Atomic absorption spectrometry method.