Abstract <p>Al–Mg alloys, commercial deformation Al alloys, have been widely applied in the fields of aerospace and automotive, however, the alloys still suffer from a lack of strength. In the present work, the effects of Sc/Er and Zr modification on the microstructure and mechanical properties have been investigated. The results prove the significant grains refinement effect in Al–Mg alloy with the Sc and Zr modification due to the formation of the coherent Al₃(Sc,Zr) phase, and the average grain size decreased from 31.2 to 21.6 μm. Meanwhile, with the Sc and Zr modification, the yield strength and tensile strength improve from 141.9 and 214.5 MPa to 180.3 and 256.8 MPa, respectively. This is attributed to the combination of Hall–Petch reinforcement and Orowan reinforcement. However, the Er and Zr modification decreases the mechanical properties of Al–Mg alloy, which is attributed to the formation of petal-like grains. In addition, notable Portevin–Le Chatelier effect was found in all three Al–Mg alloys, which is like other Al–Mg alloys. The investigation in the present work establishes a foundational basis for component screening in selective laser melting process.</p>