Abstract: Elaborated in the paper are the R&D and application of the economical CS-3Cr80SS anti-corrosion tubing/casing.With the simulated oil field CO₂ corrosive environment, the regularity of corrosive effects by various factors on the N80Q steel and CS80-3CrSS steel is studied.Also studied with the SEM are the characteristics of the corrosion product film of these two steels.And both the pipe body and coupling as made of the CS80-3CrSS are SSC tested.The study result shows that since all of their product performance indexes are very good, the economical CS80-3CrSS anti-corrosion tubing/casing are suitable for gas/oil fields with medium/light CO₂ corrosive level environment or CO₂ &H₂S co-existing corrosive environment.