During the wire-arc additive manufacturing process， Al5356 straight-wall components are fabricated by imparting lateral swings of varying frequencies and amplitudes to the welding gun. The impact of these swinging arcs on the forming quality， pore distribution， microstructure， and mechanical properties of the components is evaluated through surface waviness calculations， microstructural analysis， and mechanical tensile tests. The results show that incorporating the arc swing technique in the manufacturing process significantly enhances the forming accuracy， compactness， microstructural uniformity， and mechanical properties of the straight-wall samples. Within the experimental parameters， applying an arc swing reduces the surface waviness of Al5356 straight-wall samples by 60% compared to those produced without an arc swing. Additionally， the porosity and maximum pore diameter are decreased from over 0.65% and 33 µm to below 0.20% and 10 µm， respectively. The average tensile strength in both the X-direction （deposition direction） and Z-direction （build direction） increases by approximately 13% and 15%， respectively， while the average elongation improves by about 27% and 25%， respectively. Notably， the frequency of the arc swing has a more pronounced effect than the amplitude in enhancing surface quality， pore dispersion， and pore diameter reduction in the deposited components. High-frequency arc oscillation exerts a potent stirring effect on the melt pool， leading to a more uniform temperature distribution across the transverse direction of the deposited weld path. The observed enhancement in mechanical properties is primarily attributed to the reduction of pore defects and the homogenization of the microstructure. Therefore， the proper application of the arc swing technique in wire-arc additive manufacturing holds significant promise for improving the forming quality and mechanical properties of components.