A7N01　aluminum　alloy　with　the　thickness　of　4　mm　is　welded　by　using　fiber　laser-variable　polarity　TIG　hybrid　welding　with　filler　wire.　The　effects　of　both　welding　current　and　welding　speed　on　weld　formation　and　porisities　are　discussed.　The　microstructure　and　mechanical　properties　of　the　joint　obtained　at　optimal　welding　parameters　are　investigated.　Experimental　results　show　that　the　top　weld　width　increases　and　the　bottom　weld　width　is　unchanged　with　the　increase　of　the　welding　current.　With　the　welding　speed　decreasing,　both　the　top　and　the　bottom　width　increase,　and　the　internal　porosities　decreases.　Under　the　condition　of　laser　power　of　6　kW,　welding　current　of　180　A,　welding　speed　of　4　m/min　and　wire　feeding　rate　of　4　m/min,　the　joint　with　good　formation　and　few　welding　defects　is　obtained.　Weld　cross　section　is　characterized　by　the　wide　top　weld　width　and　narrow　bottom　weld　width.　The　microstructure　of　the　joint　is　composed　of　equiaxed　grain　zone,　columnar　zone　and　equiaxed　dendrite　zone　from　the　fusion　line　to　the　center　of　weld.　The　sizes　of　the　grains　and　equiaxed　dendrites　from　the　top　to　the　bottom　are　gradually　reduced　along　the　weld　centerline.　The　fusion　zone　hardness　is　lower　than　that　of　the　base　metal,　which　indicates　that　the　soften　zone　is　occurred　in　the　joint.　The　average　tensile　strength　of　joints　is　369.8　MPa,　which　is　approximately　83%　of　the　base　metal.　And　the　extension　rate　is　about　4%.　The　tensile　fracture　occurs　in　the　weld　zone,　and　the　fracture　morphology　is　distinctly　ductile　characteristics.　©　2016,　Chinese　Lasers　Press.　All　right　reserved.