Abstract: Uranium is an important material of nuclear fuel. Precise and accurate measurement of uranium concentration is critical to improving the nuclear facilities’ capabilities to effectively fulfill their responsibility of nuclear safeguard. The Davies-Gray potentiometric titration method is optimized by modifying the stirring speed and period and replacing the commonly used composite electrode with pure platinum wire and then the measurement method of 25-50 mg uranium sample is established. When this method is used for titrating 25-50 mg uranium solution, the relative standard deviation is 0.056 8%(n=12), which is more precise than any other methods available at home for gram level uranium titration. Besides, this method is also used for measuring the uranium concentration in UO2 pellets during inter-laboratory capability comparisons hold by IAEA in 2017. The Zscore is 0.78, less than 2, which is satisfactory.