Abstract: In this study, a chemical procedure for the routine determination of trace uranium in thorium has been developed. The simulated samples are leached with 2.5 mol/L nitric acid and separated using TEVA resin prior to ICP-MS measurements. The chemical recoveries of uranium in the method are 97.1%-100.0% (5 times), with 1 mL of stimulated samples and 12 mL of elution solutions (2 mol/L HNO₃). The presence of thorium stripped together with uranium doesn’t interfere with the determination. This method not only circumvents “cumbersome” sample matrix change, but also employs only one and pretty simple eluant (diluent nitric acid), hence those simplifications greatly facilitate the separation efficiency than before. After appropriate diluting with water, the effluents can be directly injected into the mass spectrometer and determined with calibration curve.