The growth curve of sulfate reducing bacterial (SRB) in the near-neutral pH solution (NS4), and the effect of SRB growth cycle on the pH value and the conductivity of the solution were investigated. Then the corrosion behavior of X70 steel in CO₂ containing NS4 solutions with SRB was studied by means of electrochemical impedance spectroscopy (EIS) and electro scanning microscope (SEM). The results showed that CO₂ played a role as a slowly available carbon source to maintain the growth and metabolism process of SRB, which resulted in a secondary growth phase of SRB. The organic carbon was consumed by SRB metabolism, and thereby the inorganic ions were released at the same time, which resulted in the increase of solution conductivity in the logarithmic phase of SRB growth. CO₂ was consumed as the inorganic carbon source in the secondary growth phase,while the inorganic ions were not emerged in the case, so the solution conductivity decreased. The growth cycle had little influence on pH value of the solution, which increased slightly with the increasing CO₂ concentration and time. There were circle-shaped cracks on the X70 steel surface in the bacterial solution. With the increasing CO₂ concentration in the bacterial solution, the compactness of the oxide scales formed on X70 steel surface gradually became worse, while pitting corrosion on the steel was promoted.