Abstract: In the conventional method of potentiometric titration, the concentration of potassium dichromate solution was optimized with selection of different concentrations of the solution. The electrode responded slowly during the titration procedure, thus affected the precision and accuracy of the results. An extraction spectrophotometric method for accurate and precise determination of uranium was presented. The method was based on the extraction of Cr(Ⅵ)-diphenylcarbazide purple complex using iso-amyl alcohol as the extractant. The purple complex was directly measured at 546 nm so that the uranium-chromate equivalence point can be determined. A method for precise determining uranium by extraction spectrophotometry was developed. The China national reference material of U₃O₈ (GBW04205) was determined according to the optimized experimental conditions. The relative standard deviation is 0.025% and accuracy of the method is verified by the value of China national reference material of U₃O₈.