Abstract: Elaborated in the essay are the chemical composition of CB110-5Cr anti-CO₂corrosion oil casing，and the design idea thereof.Based on the trial manufacture of the sample pipe and the measurement and evaluation of its mechanical properties，the temperatures as required for quenching and tempering process for the CB110-5Cr oil casing are determined.Through comparison the polarization curves and the autoclave test result of the said sample pipe with those of the P110 sample pipe，the former’s corrosion resistance is evaluated.The test results reveal that the mechanical properties of the CB110-5Cr anti-CO₂corrosion oil casing are in full compliance with the requirements for P110 grade products as specified under API Spec.5CT—2011，and that the impact toughness is high，and at medium or low temperature，along with increasing of the CO₂partial pressure the corrosion rate of the CB110-5Cr oil casing is going up，showing that its corrosion resistance is obviously much better than that of the P110 oil casing. However the results also show that on the other hand，in case of the temperature above 90℃，the corrosion resistance of the P110 oil casing is better than that of the CB110-5Cr oil casing.