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One crude oil pipeline lifting segment used in a oilfield in west of China leaked many times in a short time,serious corrosion and decreased wall thickness was observed near the leak position of the failure pipe.In order to find out the reason,this failure pipeline lifting segment was investigated and analyzed by macroscopic analysis,test of chemical composition,metallurgical analysis,mechanical property,scanning electronic microscopy(SEM)analysis,X-ray diffraction(XRD)analysisand corrosion simulation test.Based on the systematic analysis it can be concluded thatthe mechanical properties of the failure pipeline accord with related standards,the crude oil which conveyed in the pipeline contained a large number offormation water,because the formation water as acidic(PH value was 5.0-6.5)and contained high salinity,the materials of pipeline hadvery high corrosion rate in the crude oil,which was confirmed by corrosion simulation test.At the same time,by the reason of fluid flow changed suddenly in the pipeline lifting location,fouling deposition occurred inside the pipeline,which led to serious localized corrosion caused bysmall anode big cathode corrosion galvanic cell reaction and wall thickness decreased quickly in a short time,at last the pipeline lifting segment leaked by fluid erosion and the high speed impact of solid particles and grit in crude oil.