It　is　well　known　that　the　oxide　film　on　the　surface　of　Al-Li　alloys　has　to　be　cleaned　before　welding　in　order　to　achieve　welds　without　pores.　However　it　is　hard　work　and　may　cause　pollution　if　chemical　cleaning　is　used.　This　paper　reports　on　experiments　in　which　a　plate　of　Al-Li　alloy　was　not　treated　in　any　way　as　a　precondition　of　laser　welding.　A　DC035　CW　CO2　laser　system,　in　the　TEMOO　mode,　with　an　output　up　to　3500　W　was　employed　and　an　experimental　study　was　conducted　on　porosity　control　during　the　welding　of　1420　Al-Li　alloy　by　a　dual-　beam　laser.　The　experimental　results　show　that　the　influence　from　the　right　(upper)　surface　oxide　film　on　the　porosity　in　the　weld　is　bigger　than　that　from　backside　one　when　the　laser　welding　is　in　the　form　of　a　beam　on　the　surface　of　a　plate.　However　the　porosity　from　the　backside　oxide　film　has　a　distinct　connection　with　the　formation　of　the　inverse　weld　when　butt　joint　laser　welding　is　used.　Optimized　laser　welding　techniques　have　been　achieved　from　experiments　with　the　aim　of　decreasing　the　porosity　in　the　weld　and　increasing　the　weld　qualities.　The　tensile　strength　of　laser　welding　joint　was　also　tested　in　the　experiments.　The　data　indicate　that　the　average　value　of　tensile　strength　of　the　joints　can　be　up　to　336.1　MPa　which　is　equal　to　87.5%　value　of　substrate　alloy