2219　aluminium　alloy　with　5　mm　thickness　was　used　as　the　experimental　material,　the　metal　transfer　and　bead　formation　characteristics　of　aluminum　alloy　welding　under　different　pulse　laser-arc　arrangement　(i.　e.　different　laser　incident　points)　were　studied,　and　the　mechanism　for　the　increase　of　weld　penetration　was　analyzed.　The　results　show　that　when　the　pulse　laser　irradiates　the　base　material,　it　mainly　provides　heat　input　to　the　base　metal,　and　the　temperature　increase　of　the　base　material　helps　to　promote　the　droplet　spread　and　stabilize　the　metal　transfer　process;　when　the　pulse　laser　illuminates　the　solid-liquid　interface　of　the　droplet,　it　primarily　provides　a　recoil　force　to　the　droplet.　A　stable　＇one　pulse　per　droplet＇　transfer　is　obtained,　which　significantly　increases　metal　transfer　frequency　and　the　droplet　flight　speed.　The　welding　penetration　is　enhanced　by　the　increase　of　droplet　impact　force　on　the　molten　pool.　When　the　pulsed　laser　alternately　illuminated　the　molten　pool　and　the　droplet,　on　the　one　hand,　the　base　material　can　be　heated　to　facilitate　the　spreading　of　the　droplet,　and　on　the　other　hand,　the　metal　transfer　frequency　and　the　uniformity　of　the　bead　formation　can　be　improved.　©　2019,　Editorial　Board　of　Transactions　of　the　China　Welding　Institution,　Magazine　Agency　Welding.　All　right　reserved.