Abstract: TA15 titanium alloy plates with thickness of 29mm were butt submerged arc welded.Microstructure and mechanical properties of the joints were analyzed.It was shown that weld zone was characterised by columnar grains with net distributed acicular α phase.HAZ was composed of fully recrystallized grain zone and uncompletely recrystallized grain zone.Equiaxed recraystallized β grains contained intragranular aciular α phase.Fusion zone was consitituted of adnate columnar and equiaxed grains.Tensile strength of the joints were slightly lower than that of base metal,but elongation was only up to 50% of base metal.Fracture occurred in columnar grains in weld zone.Bending property of the joints was very poor,cracks also emerged in columnar grains in weld zone.Hardness value was highest in weld zone and it decreased gradually from HAZ to base metal.