The leaching process of uraninite ore was divided into the acidification and bacterial leaching stages, and the two stage leaching experiments and the control were conducted with 3 columns, each being charged with 20 kg uraninite ore. The ore contained 0. 113％ uranium, 1. 859％ iron and large amounts of silica and alumina. In the acidification stage, high to low concentration sulfuric acid solutions were used to acidify the uranium ore in each column until the pH of the pregnant leach solution from each column was maintained at 2. 0. The acidification lasted for 18 d and the urani um recoveries for the three columns reached about 70％. In the bacterial leaching stage, column 1, as the control, con tinued to be leached with sulfuric acid solution with pH = 2. 0, column 2, with the bacterial solution based on the indi rect leaching mechanism, and column 3, with the bacterial solution based on the direct leaching mechanism. The leac hing in this stage was continued until the concentrations of the uranium in the pregnant leach solutions from the three columns amounted to less than 50 mg/L. This stage lasted for 20 d and the final uranium recoveries for columns 1, 2 and 3 reached 73.72％, 78.97％ and 75.79％, respectively.