Abstract: Al-8.5Mg-0.78Mn-0.96Er-1.94Zr alloy is prepared by selective laser melting (SLM). The effects of laser power and scanning speed on formability and microstructure of the alloy are systematically investigated. It is found out that when the laser power is high, the energy density and thermal input of laser are high, and a lot poles are tend to form in the alloy, which will the formability of alloy. When the laser power is low, and the volumetric energy density in the range of 60 to 81 J/mm³, the relative density of the alloy is higher and the formability higher. The microharness of the SLM formed alloy is between 115HV to 140HV,and the microharness decreases overall with the increase of laser power and scanning speed. The microstructure of the alloy consists of ultrafine equiaxial and equiaxial grains. Irregular Zr-rich phases exist within the alloy. The Al₃Zr primary phase exists at the melt pool boundary, and it acts as the heterogeneous nucleation site to promote the formation of ultrafine equiaxial grains and refine grain size.