The influence of aging temperatures on the microstructure and mechanical properties of an Al-Mn-Mg- Sc-Zr alloy prepared by laser powder bed fusion (L-PBF) was systematically studied. The results show that the fabricated alloy was a dense and crack-free piece with a fine grain size of 3.51 μm and a yield strength of (547±3) MPa. When the alloy was subjected to aging at 300 °C, a large amount of highly coherent Al₃Sc nanoparticles (2-3 nm) precipitated from the Al matrix. The aged sample exhibited a high yield strength of (616±4) MPa, which can be attributed to precipitation strengthening, solid solution strengthening, and grain boundary strengthening. When the alloy was aged at a temperature higher than 300 °C, part of the dissolved Mn and Zr precipitated in the form of Al₆Mn and Al₃(Sc,Zr). When the alloy was aged at 500 °C, the Al₆Mn and Al₃(Sc,Zr) precipitates grew to approximately 600 and 30 nm, respectively, in size. Consequently, the yield strength of the alloy decreased to (372±3) MPa.