The　T-joints　of　Ti-6Al-4V　alloy　were　manufactured　by　double-sided　synchronized　laser　beam　welding　with　the　homologous　filler　wire.　The　formation,　microstructure　and　mechanical　properties　of　welded　joints　as　well　as　the　correlations　of　each　other　were　investigated.　The　results　indicate　that　the　quality　of　weld　seams　is　good　without　defects　such　as　discontinuity,　beading,　visible　cracks　or　porosity,　which　is　linked　to　the　steady　molten　pool　behavior　and　droplet　transition.　The　morphologies　of　the　heat　affected　zone　(HAZ)　located　on　the　skin　and　stringer　are　disparate.　The　microstructure　of　the　HAZ　and　fusion　zone　(FZ)　is　mainly　comprised　of　acicular　martensitic　alpha＇　phases.　The　microhardness　of　the　HAZ　and　FZ　is　higher　than　that　of　the　base　metal　(BM)　and　reaches　a　maximum　value　at　the　HAZ　near　FZ　on　the　stringer.　The　tensile　specimens　along　the　skin　and　stringer　fractured　at　the　BM　with　ductile　fracture　surfaces.