Abstract: The bell-shaped TC4 titanium alloy joint of electron beam welding were divided into three zones,namely weld seam,heat-affected zone and base metal.Considering the gradient distribution of the material strength in the heat-affected zone,the finite element model was founded.The series of software of MSC company were used to analyze the distribution of stress and fatigue life under the simulated experimental loading conditions,and the stress distribution along different paths were investigated,and the simulating results of fatigue life were compared with that of experiments.It is shown that the weld seam has noticeable effect on stress distribution of the weldment,which causes the stress concentration with the stress concentration factor of about 1.3 at the weld toe.The uneven distribution of weldment life is caused by stress concentration,so that the fatigue life of weldment is reduced.The fatigue failure usually starts at the weld toe.