In order to improve the comprehensive properties of Al-12Si alloy formed by selective laser melting (SLM), Al-12Si-(Er-Zr) alloy was prepared by SLM after the addition of Er and Zr elements by aerosol treatment. The microstructure, physical and mechanical properties of Al-12Si-(ER-Zr) alloy were studied by means of experimental tests, and the strengthening mechanism of Er and Zr elements during the SLM processing was analyzed in depth. Results show that the highest relative density of 99.2% can be obtained when the energy density reaches 57.5/mm3. There are gray Al and white eutectic Si structures in Al-12Si-(Er-Zr) alloy prepared by SLM, and the morphology characteristics of network distribution show that Er and Zr elements can significantly refine the grain size of Al-12Si-(Er-Zr) alloy. Compared with Al-12Si alloy, the hardness of Al-12Si-(ER-Zr) alloy prepared by SLM increases by 26.1%, tensile strength increases by 20%, yield strength increases by 27%, and elongation does not change significantly. The grain size of Al-12Si-(Er-Zr) alloy prepared by SLM reaches larger Schmid factor, contains more high Taylor factor, higher proportion of Brass cold rolled texture and Copper tensile texture, resulting in higher mechanical strength of Al-12Si-(Er-Zr) alloy.