Abstract: The cracking cause of corrugated pipe of stainless steel used in an electromechanical product was analyzed by means of SEM, energy spectrum and so on. The results showed that the welded joint region was sensitized during welding, subsequently, corrosion crack along the grain boundary formed by pickling, the corrugated pipe bore radial direction alternating load during the vibration test, the crack began to extend from the bottom of intergranular corrosion cracks, lastly, the crack penetrated the pipe wall. The fracture surface characterized with obvious cowrie pattern lines, that proved the corrugated pipe occurred fatigue failure.