A　hybrid　Nd:YAG　laser　beam　welding　technique　has　been　investigated　in　welding　of　aluminum　alloy　Connecting　the　filler　wire　with　one　pole　of　a　DC　power　supply　and　the　workpiece　with　the　other,　a　closed　electric　circuit　is　built.　By　this　means,　the　wire　is　resistively　preheated,　so　that　less　energy　from　the　laser　beam　is　dissipated　in　melting　the　filler　metal.　On　the　other　hand,　the　current　flowing　in　the　weld　pool　generates　a　magnetic　field　and　electromagnetic　forces　which　affect　the　fluid　flow　of　the　weld　pool　and　then　the　welding　process.　It　is　found　that　the　weld　depth　increases　and　the　weld　seam　becomes　slender　when　a　certain　current　is　supplied.　To　clarify　which　effect,　the　thermal　effect　or　the　electromagnetic　effect,　dominates,　welding　with　pure　hot　wire　was　carried　out.　The　experimental　results　demonstrate　that　the　pure　hot　wire　addition　has　no　obvious　affect　on　the　welding　efficiency　and　the　weld　cross　section,　but　worsens　the　process　instability.　Thus　we　can　conclude　that　the　influences　of　the　current　do　not　result　from　the　resistive　heat　from　the　wire,　but　the　electromagnetic　effects.　This　new　approach　provides　a　possibility　to　increase　the　processing　efficiency　and　flexibility,　improve　the　process　stability　and　weld　quality,　and　also　shape　the　seam　cross　section.