Abstract: The main shell of the fuel distributor and clamp in the aviation clamp connection structure cracked. The cracking causes of clamp connection structure were analyzed by macroscopic observation, scanning electron microscope analysis, metallographic examination and hardness test. The results show that the main crack of the fuel distributor originated from the R angle of the mounting edge and was characterized by multi-source and line source, which was a bidirectional bending fatigue crack with large initial stress. The clamp experienced fatigue cracking with large initial stress. The crack originated from the inner surface of the connecting ring, which was characterized by multi-source and line source. The uneven stress on the contact surface between the fuel distributor and the clamp was the main reason for its early fatigue fracture and the extrusion friction damage of the joint surface also promoted the initiation of fatigue cracks.