An Al plating layer was deposited on the surface of CoCrNiAlY–YSZ–LaMA dual ceramic coating by arc ion plating (AIP). The high temperature oxidation behaviors of these coatings during the air exposure were comprehensively characterized by using XRD, SEM and EDS. Results showed that LaMA coating without Al plating layer underwent severe volume shrinkage during the oxidation test, which triggered the initiation and propagation of longitudinal micro-cracks. These micro-cracks acted as the internal diffusion channels for O₂, triggering a sustained mass increase tendency, rapid TGO growth and severe elemental diffusion, and consequently resulted in a serious coating fracture. However, the coating with Al plating layer showed better high-temperature oxidation resistance and structural stability. The surface Al layer reacted with O₂ to generate an in situ dense Al₂O₃ barrier layer during the oxidation process, which prevented or delayed the internal penetration of O₂, and thus resulted in a very slow growth rate of TGO layer. The weight gain of this sample increased slightly from 8.59 mg/cm² at 20 h to 9.46 mg/cm² at 80 h. These current experimental results provided a new technical way and theoretical vision for the life-extension design of dual-ceramic thermal barrier coatings and the regulation of interfacial thermal growth stress.