Abstract: The selective laser melting (SLM) was applied to prepare an Al-Zn-Mg-Sc alloy. The microstructure and mechanical properties of the selective laser melted Al-Zn-Mg-Sc alloy was investigated before and after heat treatment. The results showed that the printed Al-Zn-Mg-Sc alloy had an anisotropic microstructure: a fish-scale-like molten pool, large columnar grains at the building plane, and small strips of grains with equiaxed grains at the scanning plane. A large number of hot cracks were found in the alloy, resulting in poor mechanical properties. However, after heat treatment, the performance of the alloy was significantly improved. After heat treatment, the Vickers hardness of the alloy increased from 91.70 to 144.27, and the tensile strength increased from 183.71 MPa to 257.53 MPa.