Abstract: With the increasing demand for high-efficiency and reliable joining of aluminum alloy structural components in avionics and related fields, nitrogen brazing of 6063 aluminum alloy still suffers from insufficient wetting/spreading and fluctuations in joint quality. In this study, 6063/6063 aluminum alloy joints were fabricated via an Al-Si filler metal at brazing temperatures of 605-625 °C. The effects of brazing temperature on the microstructure, elemental distribution, and grain/grain-boundary characteristics were systematically investigated. The results show that during the holding stage at 605 °C, the contact angle decreased from approximately 92.9° to a stable value of 65.8°, indicating diffusion-dominated wetting behavior. With increasing brazing temperature, the overall amount of lack-of-bonding regions and pore defects in the brazed seam decreased. The joint microstructure mainly consisted of α-Al, β-AlFeSi, and Si phases. EBSD analyses revealed that precipitate-enriched regions exhibited finer grains and higher KAM values, while increasing temperature promoted a higher fraction of high-angle grain boundaries (about 61.6% at 620 °C), leading to a more stable and homogenized joint structure. The shear strength exhibited a rise-then-fall trend with temperature, and the high overall performance was obtained at 615 °C.