Abstract: Based on the analysis concerning the service conditions and failure types of O.C.T.G.,it is put for-ward that the most critical issues relating to this category of oil pipes are steel grade and thread connection.The development trend of steel grade and thread connection of O.C.T.G.are discussed.Also discussed in the article are such topics of general interest as the strength-toughness mating of the hi-strength oil well pipe,the technologies of expandable pipe and continuous pipe as well as the anti-CO₂ corrosion pipe etc.