Wire and Arc Additive manufacturing (WAAM) of 2219 aluminum alloy parts is a prospective manufacturing technology in the aerospace industry. In this study, the single wall specimens of 2219 aluminum alloy were built by WAAM technology using CMT welding process. The microstructure characteristics in as deposited state, solid solution state and artificial aging state were systematically investigated. It was found that the weakness strip with more micro porosities, θ(Al₂Cu) phases and iron rich phases in the interlayer region resulted in the anisotrpic mechanical properties of the WAAM specimens. When the specimens were tensioned in the vertical direction, cracks formed easily in the interlayer region, and deteriorated the tensile strength and plasticity. In order to increase the mechanical properties of the WAAM 2219 aluminum alloy in the vertical direction, the composition of Fe and Si in the wire should be as low as possible.