Al-4.7Mg-0.7Mn-0.3Er　alloy　plates　were　welded　by　laser　beam　welding　(LBW)　and　tungsten　inert　gas　(TIG).　Mechanical　properties　and　microstructures　of　both　welded　joints　were　analyzed.　The　results　showed　that　the　tensile　strength　of　LBW　joint　was　315　MPa,　which　was　approximately　10%　higher　than　that　of　TIG　welded　joint.　This　was　attributed　to　the　fine　grains,　dispersed　primary　Al3Er　phase　and　low　Mg　evaporation　in　LBW　weld.　Equiaxed　grains　with　average　size　of　30　mu　m　were　obtained　in　the　fusion　zone,　which　were　much　smaller　than　that　of　90　mu　m　in　the　fusion　zone　of　TIG　joint,　due　to　the　low　heat　input　during　LBW　process.　Moreover,　finer　primary　Al3Er　particles　were　uniformly　distributed　in　the　LBW　joints,　which　resulted　in　a　substantial　increase　of　nucleation　rate　in　LBW　welds.　In　addition,　it　was　also　found　that　Mg　concentrations　in　the　fusion　zones,　in　both　TIG　and　LBW　joints,　were　lower　than　that　of　the　base　one　tested　by　EPMA.　The　burning　loss　rates　of　Mg　in　TIG　and　LBW　joints　were　36%　and　22%,　respectively.　(C)　2012　Elsevier　Ltd.　All　rights　reserved.