The　method　of　CO2　laser　welding　with　filler　wire　was　used　to　join　the　dissimilar　high　strength　aluminum　alloy　2024　and　7075.　This　paper　represented　the　effect　of　welding　procedure　to　the　appearance　of　weld　bead,　the　porosity　and　the　instability　of　the　welding　process.　The　mechanism　was　studied.　By　analyzing　the　microstructure　and　strengthening　phase　of　weld　bead,　the　causes　of　defects　and　the　impact　on　the　mechanical　property　are　discussed.　Moreover,　we　contrasted　the　microstructure　and　mechanical　properties　of　the　weld　beads　welded　by　filling　two　different　weld　wires,　and　analyzed　the　reason　of　their　differences.　©　2012　IEEE.