The　twin　spot　laser　welding　could　improve　the　weld　appearance　and　inner　quality　obviously.　The　aluminum-lithium　alloy　is　regarded　as　one　of　the　important　candidates　material　for　modern　aerospace　structures.　In　this　article,　the　microstructure　of　twin　spot　laser　welding　joint　of　3mm　aluminum-lithium　sheet　was　observed.　The　mechanical　properties,　such　as　the　microhardness　and　the　tensile　properties　at　the　room　temperature　were　also　tested,　and　the　fractography　was　also　observed.　The　results　indicate　that　the　microstructure　of　the　joint　is　columnar　grain　and　equiaxed　dendric　grain,　and　the　stratified　line　appeared　in　the　columnar　grain　zone.　The　HAZ　could　be　performed　as　fine-grain　zone.　Meanwhile,　the　microhadrness　of　the　joint　could　reach　80%　of　parent　metal　and　the　tensile　strength　of　joint　could　be　increased　to　above　85%　of　parent　metal.　Besides,　the　tensile　fractography　of　joint　is　presented　by　ductile　rupture.　As　a　result,　The　twin　spot　laser　welding　is　proved　to　be　a　good　method　to　realize　the　welding　of　5A90　aluminum-lithium　alloy　sheet.