Aluminum-lithium　alloys　are　considered　to　be　one　of　the　most　ideal　light-weight　materials　for　aerospace　applications.　2198-T851　with　thickness　of　1.76　mm　is　welded　with　filler　wire　ER4047　by　using　a　high　power　fiber　laser.　The　effects　of　the　laser　power,　welding　speed　and　wire　feeding　velocity　on　solidification　cracking　susceptibility　and　microstructures　are　investigated,　as　well　as　the　joint　microstructure　and　mechanical　properties　under　the　optimal　welding　process.　The　results　indicate　that　a　joint　with　good　surface　appearance　and　no　hot　crack　is　obtained　with　the　optimal　welding　parameters　of　4　kW　laser　power,　4　m/min　welding　speed　and　4　m/min　wire　feeding　velocity.　The　average　tensile　strength　of　joints　is　342　MPa,　and　reaches　65.4%　of　the　tensile　strength　of　base　metal.　The　bond　is　the　weakness　region　of　the　joint.