The influence of wire compositions with different Cu, Fe and Si content on the microstructures and mechanical properties of heat treated WAAM single-walls was studied. It was found that the yielding strength of WAAM samples was low when the Cu content (5.3wt%) in wire was insufficient. When the Cu content in wire slightly exceeded the maximum solid solubility of Cu (5.65wt%) in α(Al), the yielding strength of WAAM samples increased without deteriorating the plasticity although there were some residual θ(Al₂Cu) phases. When the wire had approiate Cu content (5.8-6.5wt%) with low Si content(<0.08wt%), the yielding strength of WAAM samples decreased with the increasing of Fe content due to the redueced amount of strengthening phases and increased amount of θ phases and α(Fe) compounds. When the wire had approiate Cu content with high Fe and Si content(>0.15wt%), the plasiticity in vertical direction of WAAM samples deteriorated due to the existing of acicular β(Fe) compounds in the interlayer region of the samples. Using the wire with low inpurities content (Si<0.08wt%,Fe<0.15wt%) and approiate Cu content (5.8-6.5wt%), the WAAM samples possesed the excellent mechancial properits with average tensile strength, yielding strength and elongation after fracture exceeding 440MPa, 300MPa and 10%, respectively.