Abstract: Fracture failure happened in a ZL102 aluminum alloy equalizing ring splint of an alternating current (AC) transmission line. Physical and chemical tests were carried out to the on-site failure component, and electrochemical tests and corrosion morphology observation of ZL102 aluminum alloy were carried out in the simulated on-site corrosion environment, so as to analyze the failure process of the material. The results show that casting defects were the key cause of the failure of the aluminum splint. Under the action of alternating current, casting defects were worked as the failure site. The failure process of the ZL102 aluminum alloy was mainly divided into the protection stage of corrosion product layer, the initiation and development stage of pitting corrosion and the longitudinal development stage of pitting pit. With the increase of corrosion time, the open-circuit potential showed a change rule of basically constant→forward migration→basically constant, the corrosion current density showed a change rule of slowly increasing→rapidly increasing→slowly increasing, and the charge transfer resistance continued to decrease, but the decreasing speed gradually slowed down.