As a kind of clean, efficient and relatively safe energy, nuclear energy has been widely used around the world. The high-level radioactive waste (HLRW) generated in the nuclear has also become a major risk, so the disposal safety of HLRW will be especially important. The planned concept of China's HLRW disposal program is a shaft-tunnel model located in saturated zones in granite. The metal container for sealing the HLRW is the key because its interaction with the ground water will lead to the leak of the HLRW during the long repository time. Beishan is a selected repository area and the ground water contains a bicarbonate (HC{O}_3^{-}) buffer solution. Therefore, as a candidate material of the container, the active/passive state of low carbon steel in the ground water with is of significance, which determines the container's service life. The active state will ensure that the container achieves the designed life under general corrosion, and moreover the passive state will degrade the container's life under stress corrosion cracking (SCC) caused by pitting corrosion. In this work, the effect of HC{O}_3^{-} on the corrosion behavior of low carbon steel was examined in deaerated bicarbonate solutions (pH 8.3) over 50 d. The presence of HC{O}_3^{-} enhanced both the anodic Fe dissolution and cathodic hydrogen evolution reaction. The situ-measurement of corrosion potential revealed that the increased concentration of HC{O}_3^{-} led to the high corrosion potential. When the concentration of HC{O}_3^{-} was 0.01 mol/L, the corrosion potential was in the active region. When the concentration of HC{O}_3^{-} was higher than 0.02 mol/L, the corrosion potential was in the passive region. EIS results showed that the charge transfer resistance, film resistance and the diffusion impedance increased with the increasing HC{O}_3^{-} concentration. Results of XRD analysis illustrated that the key corrosion products were mainly composed of Fe₃O₄ and α-FeOOH.