Abstract:CO2 O2 column leaching test for sandstone type uranium deposit was conducted in laboratory. The results show that uranium recovery is 67.05% when L/S is 5.20 (mL/g). HCO3- concentration is the key factor affecting uranium leaching, and maintaining HCO3- concentration as 800 mg/L below can produce an ideal uranium leaching outcome. Both uranium content in ore and concentration of resolved uranium drop with leaching process. Ca2 and SO42- concentration in solution rise due to interaction between lixivium and calcium carbonate and pyrite in ore. In order to effectively prevent precipitation of calcite and dolomite, pH value should be controlled at 6.6 below, because calcite and dolomite are to be in supersaturation state upon pH value of 6.6 above. Though gypsum does not reach saturation during column leaching, a continuous rising tendency of Ca2 and SO42- concentration in solution should be noted to avoid gypsum precipitation and aquifer block in in-situ leaching practice.