Abstract: The system of three-element complex drive injection section solution simulated in laboratory,electrochemical impedance spectroscopy, potentiodynamic polarization curve, scanning electron microscopy and X-ray powder diffraction were used to study the corrosion behavior of 20^# carbon steel in the injection solution.The results showed that there were a large amount of sulfate-reducing bacteria(SRB), a small amount of iron bacteria(IB) and total general bacteria(TGB) in the injection solution. The corrosion rate of carbon steel reached the highest at the initial stage of immersion due to Cl^- action, and then decreased with the formation of corrosion products and biological film. The corrosion rate of carbon steel was accelerated due to the uneven thickness of biological film and the formation of FeS at the later stage of immersion.