Abstract: The oil pipe of a certain well broke during operation. The fracture cause of the tubing was analyzed using macroscopic observation, chemical composition analysis, scanning electron microscopy and energy spectrum analysis, mechanical property testing, metallographic examination. The results show that the oxygen content in the oil pipe medium was high, and dissolved oxygen corrosion caused material perforation. The inner wall of the oil pipe at the perforation site experienced circumferential erosion. With the extension of operation time, the erosion caused thinning of the pipe wall, resulting in stress concentration at the thinning and perforation sites, ultimately led to low stress brittle fracture of the oil pipe.