The　ductile　damage　behaviour　of　laser　welded　joints　for　titanium　alloy　and　Al　-　Li　alloy　sheets　was　analysed　by　the　finite　element　method　following　Gurson　-　Tvergaard　-　Needleman　model　(GTN　model).　The　parameters　of　GTN　model　were　identified　by　an　inverse　identification　technique,　according　to　uniaxial　stress　-　strain　curves.　The　stress　-　stain　curves　for　weld　metal　(WM)　were　determined　by　microtensile　tests.　It　was　found　that　the　damage　of　the　over　matched　titanium　alloy　joints　mainly　occurred　in　the　base　metal　and　the　damage　evolution　became　faster　with　increasing　width　of　the　WM.　The　damage　of　the　under　matched　Al　-　Li　alloy　joints　mainly　occurred　in　the　WM　and　the　damage　resistance　of　the　joints　increases　with　increasing　width　of　the　WM.