A　widely　used　high　strength　aluminum　alloy　A2219　is　welded　with　CO2　laser　adopting　a　new　nozzle　and　PFL-1A　powder　deliver　machine.　The　influences　of　the　parameters　of　the　nozzle　and　the　laser　on　the　welding　process　and　the　utilization　ratio　of　the　powder　are　researched　during　laser　welding　with　powder.　The　observed　result　of　the　experiment　is　analyzed　on　the　base　of　the　picture　collected　by　the　high-speed　camera　together　with　the　data　from　the　Laserscope　UFF100,　and　the　optimized　parameters　ranges　are　obtained.　The　experiment　results　show　that,　only　when　the　powder　beam　aims　at　the　area　that　is　near　the　crystallization　edge,　and　0.5-1　mm　away　from　the　facula,　it　can　be　sure　to　enter　the　weld　pool　efficiently.　When　a　certain　amount　of　powder　is　given,　welding　speeds　need　to　be　matched　with　proper　power　and　power　density　to　make　sure　that　the　powder　can　be　utilize　availably.　Finally,　the　well-formed　weld　with　proper　exceeded　height　as　well　as　the　stable　welding　process　can　be　obtained　through　optimizing　the　parameters.