Employing the first-principles approach grounded in density functional theory, the interfacial properties of the Al (111)/HfB₂ (0001) were investigated to provide a basis for understanding the reinforcement mechanism in HfB₂ ceramic nanoparticle-strengthened aluminum alloys. Our comprehensive investigation demonstrates that among six structurally distinct Al (111)/HfB₂ (0001) interfaces, the B-terminated H stacking(H-B) interface characterized by the aluminum atoms occupying positions above the second-layer atoms of the HfB₂ substrate exhibits superior interfacial stability, as evidenced by its maximal work of adhesion (4.74 J/m²) and minimal interfacial energy (-0.54 J/m²).The disparity in charge density and partial density of states further elucidate that H-B interface display pronounced covalent bonding characteristics, while the Hf-terminated H stacked (H-Hf) interface is dominated by metallic interactions. The exceptional stability of the H-B interface promotes coherent epitaxial growth of α-Al on the HfB₂ substrate, while simultaneously inducing grain refinement in primary α-Al phases, thereby mechanical properties of metal matrix.