Abstract: The effect of sample digestion time and temperature on the determination of U(Ⅵ) and U(Ⅳ) in uranium ores and uranium-bearing rocks was carried out. And the relationship between U(Ⅵ) and total uranium in samples with both high (≥100 μg/g) and low (≤100 μg/g) contents of uranium was also discussed. The results indicate that U(Ⅵ) and U(Ⅳ) can be extracted and determined effectively under digestion temperature of 65℃ in 3 hours. The content of total uranium equals to the sum of U(Ⅵ) and U(Ⅳ) for the samples with high uranium content (≥100 μg/g). However, the content of U(Ⅵ) can be expressed as an equation of w =(A₅₆₀/A₅₈₄)×w(U_total) for the samples with low uranium content (≤100 μg/g), which can be used to calculate the contents of U(Ⅵ) and U(Ⅳ) in the samples when total content of uranium is obtained by the determination at different wavelengths, which greatly simplifies the analysis procedure and improves the analysis efficiency.