Abstract: To be determined U(Ⅳ) and hydrazine nitrate in exist together, chromium(Ⅵ)and 1,10phenanthroline is used individually as oxidation titrator and indicator for U(Ⅳ),and N-bromineimino and methyl red is used individually as oxidation titrator and indicator for hydrazine nitrate，U(Ⅳ) and hydrazine nitrate in the same sample is determined sequentially in the nitric acid by adjusting concentration of nitric acid. Results show that the precision is better than 2.0% when the mass concentration of U(Ⅳ) is ranged over 5.5～205mg/mL;and the precision is better than 2.0% when the concentration of hydrazine nitrate is ranged over 0.05～1.0mol/L.