Biological leaching of uranium from low-grade uranium ore was conducted in a draught-tube reactor to establish the rates of oxidation of ferrous iron and leaching of uranium, and the identification of dynamic characteristics. Overall uranium leaching process includes a sequence of two steps, the biological and the chemical processes, in which the biological step is the rate limiting. In the leaching by using a microorganism, Thiobacillus ferrooxidans, over 90% of uranium was leached from low-grade uranium ore within 14 days. An autocatalytic kinetic mechanism was proposed for the overall leaching process. Based on the proposed kinetic mechanism, the change in fractional conversion of ferrous iron and the overall rate expression in terms of fractional conversion of uranium were derived. The conversion of uranium predicted by these equations was in good agreement with the experimental data. The N-tanks-in-series model with plug flow recycle was employed to depict the dynamic characteristics of the draught-tube reactor. The residence times in the N-tanks-in-series and plug flow regions were found to be 1.88 sec and 2.50 sec, respectively with a variance of 0.05.