Abstract: The determination of trace uranium in sulfuric acid by measuring the laser induced fluorescence of uranyl ions with a N2 laser and a boxcar integrator has been investigated. Both a wavellength dispersive technique and a time-resolved technique were used. The effects of the concentrations of sulfuric acid and sulfate radical on the intensity and lifetime of uranium fluorescence have been measured. At low concentration of sulfuric acid, the intensity of uranyl fluorescence increases rapidly with ah increase of sulfuric acid concentration, and, as the concentration of sulfuric acid is more than 6 M, a saturation value of the intensity is reached. The influence of the concentration of sulfuric acid on the lifetime of uranyl fluorescence has also been examined. The fluorescence lifetime is 12 us to 46 μs for a concentration of H2SO4 at 0.5 to 8.0 M.The effects of the interference of other ions in nature water on the determination of uranium have been measured. It has been shown that the detection limit is better than 0.03 ppb and the precision is±7% at 0.5 ppb level in 6M H2SO4 mediun. There are no interference from a 10,000-fold amount of Na+, K+, NH4+, Mg2+, Ca2+, A13+, NO3-, and PO43-, and a 1,000-fold amount of Fe3+ and Mn2+.Chloride ion interferes strongly, but for an amount of 100-fold of uranium does not cause significant error in the results.The laser induced fluorescence method can be used in the analysis of trace uranium for natural water, effluents, biological and environmental samples.