The　microstructures　and　corrosion　behaviors　of　AA2198-T851　alloy　and　weld　were　analyzed　under　corrosive　conditions.　Weld　was　formed　using　an　innovative　fiber　laser　welding　process　with　AA2319　Al-Cu　filler　wire.　The　metallurgic　morphology　and　distribution　of　the　chemical　compositions　were　determined　using　imaging　techniques　such　as　optical　micrograph,　scanning　electron　micrograph,　high-resolution　transmission　electron　microscopy,　energy-dispersive　X-ray　spectrometry　and　X-ray　diffraction.　Corrosion　was　evaluated　using　an　immersion　test　and　electrochemical　impedance　spectroscopy　in　3.5%　NaCl　solution　at　room　temperature.　Results　indicate　that　the　parent　alloy　suffered　from　pitting　corrosion　during　the　initial　4-h　immersion　which　was　caused　by　the　inhomogeneous　distribution　of　its　chemical　components　and　the　different　intermetallics　formed　during　the　rolling　process.　The　weld　experienced　dendritic　boundary　corrosion　under　the　same　conditions　due　to　the　addition　of　the　Al-Cu　filler　and　rapid　solidification　during　laser　welding,　which　led　to　the　precipitates　Cu　enrichment　along　the　grain　boundary.　When　a　welding　joint　was　immersed　in　the　solution　for　5　days,　a　big　crack　was　observed　across　the　center　of　the　weld.　In　comparison,　there　was　good　corrosion　resistance　in　the　heataffected　zone　with　a　compact　protective　film.