Abstract: Fluorescent ramification was formed when sulfometuron-methyl was irradiated by ultraviolet radiation.The photochemical fluorescence (PCF) characteristic of fluorescent ramification in various solvents (water,dimethyl sulfoxide,methanol)and colloid solution were tested.Physicochemical variable influencing the sensitivity of the method have been optimized.The relevant factors such as the effects of the solvents system,acidity and the time for illumination were optimized and thus a novel PCF analytical method was developed for the determination of sulfometuron-methyl in water samples by adding cetyltrimethylammonium chloride colloidal dispersion.Its found that CTAC colloidal dispersion (2×10-3 mol/L) with pH 9 and illuminating 150 s were the best conditions to determine sulfometuron-methyl by PCF method.Under the optimum experiment conditions,the limit of determination was 7 μ g/L,the relative standard deviation was 1.3%.The method was successfully applied to the analyze remains of sulfometuron-methyl in nature water,and the average recovery was 96.9% ±2.2%.It indicated that PCF analytical method established would be reliable in determination of sulfometuron-methyl residue in water.