Abstract: Regarding the bended pipe cracking in inlet gathering pipeline section in complex station of Tahe Oilfield, by analyzing the macro-morphology, chemical composition, mechanical property, metallographic structure, the appearance and composition of corrosion product collected from the failure sample, the cracking reason is determined. Result shows that the low quality pipe material produces unacceptable flexibility and hardness; sulfide stress cracking occurs since the oil transported contains water (>60%), sulfur (1.64%) and H₂S; the medium transported contains high content Cl^－ which boosts the stress corrosion cracking; the hardness of the bended pipe material is greatly higher than that of requirements in relative standard, which makes it sensitive to stress corrosion cracking.