A　stress　and　distortion　mitigation　technique　for　Gas　Tungsten　Arc　Welding　(GTAW)　of　titanium　alloy　Ti-6Al-4V　thin　sheet　is　presented.　The　proposed　welding　technique　incorporates　a　trailing　heat　sink　(an　intense　cooling　source)　with　respect　to　the　welding　torch,　and　it　is　also　called　the　Dynamically　Controlled　Low　Stress　No-Distortion　(DC-LSND)　technique.　The　development　of　this　mitigation　technique　is　based　on　both　detailed　welding　process　simulation　using　the　advanced　finite　element　technique　and　systematic　laboratory　experiments.　The　finite　element　method　is　used　to　investigate　the　detailed　thermomechanical　behaviour　of　the　weld　during　conventional　GTAW　and　DC-LSND　GTAW.　With　detailed　computational　modelling,　it　is　found　that　by　the　introduction　of　a　heat　sink　at　some　distance　behind　the　welding　arc,　a　saddle　shaped　temperature　field　is　formed　as　a　result　of　the　cooling　effects　of　the　heat　sink;　the　lowest　temperature　exists　in　the　zone　where　the　heat　sink　is　applied.　High　tensile　action　on　the　surrounding　zone　is　generated　by　abrupt　cooling　and　contraction　of　the　metals　beneath　the　heat　sink,　which　increases　the　tensile　plastic　strain　developed　during　the　cooling　process　and　decreases　the　compressive　plastic　strain　developed　in　the　heating　process,　and　therefore　mitigates　the　residual　stresses　and　plastic　strains　within　and　near　the　weld.　The　experimental　results　confirmed　the　effectiveness　of　the　DC-LSND　technique　and　the　validity　of　the　computational　model.　With　a　proper　implementation　of　the　DC-LSND　technique,　welding　stress　and　distortion　can　be　reduced　or　eliminated　in　welding　titanium　alloy　Ti-6Al-4V　thin　sheet,　while　no　appreciable　detrimental　effects　are　caused　on　the　mechanical　properties　of　welded　joints　by　applying　the　heat　sink　in　the　GTAW　process.