This article uses selective laser melting （SLM） to print and form AlMgScZr alloy， and analyzes the influence of different laser powers on the density， surface morphology， microstructure， and mechanical properties of printed samples. In the range of laser power from 80W to 240W， the packed density of AlMgScZr alloy first increases and then decreases， reaching its maximum value at a laser power of 200W，with a maximum packed density of 99.6%.The tensile strength and packed density of AlMgScZr alloy are closely related.In a nearly fully compact state，the mechanical properties of the alloy reach their optimal level， with tensile strength and elongation of 492 MPa and 18.4%，respectively. Due to the addition of Sc and Zr elements，a Al₃（Sc，Zr） phase is formed inside the alloy coherent with the matrix.Al₃（Sc，Zr） phase can serve as an effective nucleation particle to promote grain refinement， and its strengthening mechanism mainly includes fine grain strengthening and precipitation strengthening.