Abstract: While an engine was returned to the factory for decomposition inspection, it was found that the swirl plate had cracks. Macroscopic observation, fracture analysis, microstructure inspection, grain size inspection, as well as thermal stress and vibration stress analysis were carried out to find out the failure cause. The results show that the cracking of the swirl plate is high-cycle fatigue cracking. The circumferential cracks of the swirl plate are mainly related to the damage caused by large local deformation during stamping by improved punching die. The damage caused by large deformation reduced the anti-fatigue performance of the indentation of the swirl plate. Under the co-effect of thermal stress and vibration stress, cracks formed, and then propagated circumferentially along the indentation caused by the punching die.