Abstract: AlSi10Mg alloys with different mass fractions (0-0.5%) of Zr were formed by selective laser melting, and treated by solution and aging. The effect of Zr on microstructure and properties of the alloy was studied. The results show that the alloys before heat treatment were mainly composed of α-Al phase and eutectic silicon phase. ZrAlSi phase was formed in the alloy after adding Zr. With increasing Zr addition, the α-Al phase and the eutectic silicon phase were refined first and then coarsened, and the refinement effect was the best when the mass fraction of Zr was 0.3%, while the size of ZrAlSi phase continued to increase. After heat treatment, the structure was further refined, and a massive ZrAlSi phase appeared when the mass fraction of Zr was greater than 0.3%. The hardness and compressive strength of the alloy increased first and then decreased with increasing Zr addition, and reached the peak when the mass fraction of Zr was 0.3%. Heat treatment further improved the mechanical properties of the alloy.