Abstract: Fatigue test was carried out for commercial pure titanium that have nano-crystallized in surface by high-energy shot peening.The result indicates that the improvement of the fatigue limit is due to the nano-crystallization and severe plastic deformation in the surface layer induced by high-energy shot peening.The observations of fracture surface under SEM found that fatigue cracks initiation area exists mostly in surface and in subsurface.In case of the fatigue cracks initiation area in surface,specimen exhibits longer fatigue life.In the other case,the surface damage of specimen by high-energy shot peening results in short fatigue life or instant break.