Abstract: A gas pipeline in a certain oilfield experienced perforation. The causes of pipeline perforation were studied using methods such as macroscopic observation, wall thickness measurement, chemical composition analysis, metallographic examination, mechanical property testing, scanning electron microscopy and energy spectrum analysis. The results show that the cause of weld seam perforation and leakage was the deposition of solid particles carried by natural gas, which formed crevice with the inner surface of the incomplete weld seam. Under the action of aqueous and acidic media, the pipeline underwent crevice corrosion, the weld seam anodic dissolution, and ultimately led to corrosion perforation of the pipeline.