The　Al-7Si-0.6　Mg　alloy　with　added　rare　earth　erbium　(Er)　was　prepared　by　laser　powder　bed　fusion　(LPBF)　technology,　and　the　effect　of　heat　treatment　on　the　microstructure　and　mechanical　properties　was　studied.　The　addition　of　Er　introduces　Al3Er　to　the　molten　pool,　which　can　effectively　hinder　the　epitaxial　growth　of　the　columnar　crystal.　The　effect　of　rapid　cooling　and　the　addition　of　Er　can　also　modify　eutectic　Si　particles,　resulting　in　an　ultrafine　eutectic　network　cellular　structure.　Moreover,　the　as-built　samples　have　an　excellent　tensile　strength　exceeding　438　MPa　and　a　ductility　of　over　8%;　furthermore,　such　excellent　mechanical　properties　are　associated　with　small　grains,　a　continuous　Si　network,　and　extremely　oversaturated　solid　solubility.　After　heat　treatment,　LPBF-processed　alloy　samples　exhibit　superior　mechanical　properties,　especially　after　direct　age　treatment,　which　can　mainly　be　attributed　to　the　precipitation　strengthening　effect　introduced　by　nanosized　precipitates.(C)　2022　The　Author(s).　Published　by　Elsevier　B.V.