Abstract: Time-resolved fluorescence spectrophotometry is used in determination of uranium in HLLW. From a solution of 2-3mol/L HNO₃, uranium in HLLW can be quantitatively extracted by 30%TBP-OK, while most fission products and large quantity of salts are hardly extracted. And then, 4 mol/L NaNO₃ in a solution of 2 mol/L HNO₃ is used to wash the organic phase. Uranium is back-extracted by w =5% (NH₄)₂CO₃ solution. Finally, time-resolved fluorescence spectrophotometric method is used for analysis of the stripping aqueous phase. Satisfactory results are obtained. This method is characterized by its high recovery (95%-101%) and high precision (better than 2%). The method has been successfully used for analysis of HLLW from the spent fuel reprocessing pilot plant, and water-samples from neutralization pit with satisfactory results. Meanwhile, it can also be expected to determine uranium concentration in high-salinity and complex samples, such as environmental samples.