Abstract: Elaborated here in the essay are the design and development history of the martensitic stainless steel OCTG(Oil Country Tubular Goods),the CO₂ corrosion mechanism,and the factors as affecting the corrosion resistance of the martensitic steel. It is found that increasing the effective Cr content and reducing the delta ferrite are the keys to improving the performance through research on the chemical composition design. Also discussed is the CO₂ corrosion theory,particularly the influence on CO₂ corrosion due to trace H₂S. Furthermore discussed are the effects on the corrosion resistance of the martensitic stainless steel by the material and environment factors. The temperature has the most significant influence on the corrosion resistance, the H₂S content can restrict the application of the materials,and both pH and the Cl ^- content can affect the process of the cathodic reaction. Finally the research direction of the martensitic stainless OCTG is prospected.