Abstract: The cracking reason of 7A09-T6 high strength aluminum alloy fluid connector was analyzed by macroscopic and microscopic morphology observation, energy spectrum detection and theoretical calculation. The results show that the crack initiated from the mouth of the fluid connector shell, expanded along the axial direction to the root, and penetrated the wall thickness. The cracking mode was stress corrosion cracking. The reason was that the 7A09-T6 high strength aluminum alloy was a stress corrosion sensitive material, the hard anodic oxidation process introduced the corrosion medium S element, and the connector was in a tensile stress and wet environment.