Abstract: Ultrasonic fatigue tests are carried out to investigate very-high-cycle fatigue property of TC11 titanium alloy electron beam welding joint. The results show that fracture still occurs in the TC11 titanium alloy welded joints after 107 cycles, and the S-N curve presents a continuously decreasing shape. No obvious inflection point can be found in S-N curve. Most of the specimens fracture in the base metal and fatigue properties of weld joint and HAZ are better than the base metal due to the microstructure of welded joint. The morphology of specimen is observed by scanning electron microscope. It is proved that most of fatigue cracks initiate at the surface. However, fatigue crack initiation site transforms from surface to subsurface in the longer life regime.