Objective To develop a new method for the determination of trace silver in water by flame atomic absorption(FAAS) after cloud point extraction.Methods Diethyldithiophosphate(DDTP) and triton X-114 were respectively used as the chelating agent and surfactant.The effects of experimental conditions such as acidity,concentration of chelating agent,surfactant and methanol,equilibration temperature and time,interference ion on cloud point extraction were investigated.Results Under the optimum condition,0.5 ml of 0.1 mol/L DDTP solution,0.5 ml of 50 g/L Triton X-114 and 5 ml of 1 mol/L hydrochloric acid were added and the volume was made up to 50 ml.The mixture was heated in a thermostatic bath at 40 ℃ for 15 min,the linear range of determination for silver was 0-100 ng/ml,the equation of linear regression was A = 0.005 8cAg+ 0.001 6,r = 0.999.The detection limit was 0.83 ng/ml,the recovery rate was in the range of 97%-105%,and the relative standard deviation was 3.1%(n=11) for 20 ng/ml Ag.There was no significant interference for silver solution containing 5 000 times of K+,Na+,Ca2,Mg2,NO3,SO4 + +-2-and Cl-,1 000 times of Al3+ and Zn2+,500 times of Fe2+ and Mn2+,100 times of Pb2+ and Cu2+.Conclusion The method is rapid,accurate,simple and applicable to the determination of trace silver in water samples.