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The technology of laser deposited repair was used to repair TA15 alloy with milling groove damage, and the fatigue crack nucleation and growth behaviors were investigated. Fatigue fracture surfaces and longitudinal sections of specimens were examined by optical microscopy and scanning electron microscopy. Results indicated that specimens were broken in the repaired zone and the fatigue properties are microstructure-sensitive. The crack nucleation region was characterized by the crystallographic cleavage facets of α lamellae and tearing of β matrix. The size and morphology of the cleavage facets were the same with α lamellae. The crack tended to propagate along the border of α lamellar and its propagation direction was parallel or perpendicular to α lamellar. After solution-aging treatment, the microstructure-sensitive size reached individual small units of a single lamellae, presenting a single α/β tearing deformation along the misalignment of silp direction in two colonies and a clear arrangement of bunch-α ". A finer, more oriented lamellar structure were obtained to make it easier for fatigue crack deflection, increased the length of the crack path, thereby consuming more crack propagation energy.