Abstract: Wire arc ddditive manufacturing(WAAM) is a novel manufacturing approach characterized by high efficiency and low cost, which is suitable for fabricating large-scale and complex aluminum alloy components. However, critical technical issues including grain coarsening, unstable structural formation, and anisotropic mechanical properties caused by heat accumulation during the additive manufacturing process severely restrict its application in high-end manufacturing fields.Accordingly, aiming to optimizing the performance control and shape control processes in WAAM, this paper systematically investigated the influence of TiB₂ powder-assisted assisted TIG process on the microstructure and mechanical properties of 5183 aluminum alloy fabricated by WAAM. Real-time observation was conducted for the thermal process during TIG WAAM using infrared thermal imaging. It is found that severe heat accumulation and overheating tends to occur in the upper region of conventional 5183 aluminum alloy single-wall components. The addition of TiB₂ particles effectively reduces the peak temperature of the molten pool and suppresses heat accumulation in the component, leading to a more stable temperature cycle. Meanwhile, the particles significantly promotes the nucleation of equiaxed grains and inhibits grain boundary migration, reducing the grain size from 120 μm to 65 μm. The longitudinal tensile strength of the formed parts reaches 320 MPa with an elongation of 33%, while the transverse tensile strength ranges from 305 MPa to 320 MPa with an elongation of 27.9% to 31%. The results demonstrate that TiB₂ powder-assisted assistance effectively refines the microstructure and improves the mechanical properties of 5183 aluminum alloy fabricated by TIG-WAAM