In　the　fields　of　medical　equipment　manufacturing　and　aerospace　engineering,　aluminum　alloys　are　widely　applied　to　make　the　shells　of　the　electronic　devices.　Laser　welding　is　considered　as　a　suitable　technology　to　produce　those　components　for　the　low　heat　input　and　high　joint　strength.　In　this　paper,　a　4.0kW　disc　laser　was　used　to　weld　2024　aluminum　alloy　sheet　with　a　thickness　of　1mm.　The　difference　of　the　weld　formation　with　and　without　filler　powder　was　discussed.　The　experimental　results　show　that　the　weld　sizes　of　profiles　in　welding　with　filler　powder　are　higher　than　that　in　autogeneous　welding　with　the　same　welding　parameters.　With　the　increasing　of　the　defocusing　distance　in　welding　with　filler　powder,　the　weld　depth,　width　and　cross　section　area　decrease　at　first,　then　increase　and　go　down　at　last,　while　the　weld　depth　decreases　drastically　in　autogeneous　welding.　The　powder　filled　improves　the　efficiency　of　welding.