In this work, a dual-phase synergistic enhancement method was employed, leveraging the unique advantages of Er and TiB₂ to strengthen Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion (L-PBF). Spherical powder of 0.5wt% Er-1wt% TiB₂/Al-Mn-Mg-Sc-Zr nanocomposite material was prepared using vacuum homogenization technology, and the density of the sample prepared using L-PBF process reached 99.8%. X-ray diffraction (XRD) analysis showed the presence of Al₃Er diffraction peaks, and EBSD results showed a decrease in texture strength. The added Er and TiB₂ nano-reinforced phases act as heterogeneous nucleation during the L-PBF forming process, hindering grain growth and effectively refining the grains. The results showed that after adding Er and TiB₂ dual-phase nano-reinforcement, the tensile strength and elongation at break of the L-PBF deposited sample reached 550 MPa and 18.7%, respectively, which were 13.4% and 26.4% higher than those of the matrix material. This work explores the strengthening mechanism and toughening mechanism of Er-TiB₂, and the relevant research results provide experimental support for obtaining the ideal mechanical properties of high-strength and tough aluminum alloys and the application of additive manufacturing components.