Abstract: The TC11 titanium plates with 40 mm of thickness was welded by electron beam and full penetration joint without defects was obtained.Results show that the microstructures in the fusion zone are acicularα'and directional columnar grains.With the increases of fusion zone depth,the acicularα'becomes finer and denser,which leads to higher microhardness.The microhardness of fusion zone is higher than those of base metal and heat affected zone.The welded joint shows higher ultimate tensile strength and yield strength,but lower elongation and reduction of area compared with base metal.The tensile properties of welded joints exceed the industry requirements for TC11.All tensile samples fail in BM with the fracture type of ductile fracture.