An experimental investigation on the mechanical mechanisms of fatigue micro-crack initiation and propagation of a nickel-based superalloy is presented. By coupling digital image correlation method and scanning electron microscope, the fatigue residual strain distribution at the grain scale has been obtained. The results showed that there is a trend of accumulation for the residual strain. Micro-cracks are more likely to initiate in or near the areas with particularly large residual strain, and propagate along the large-strain paths. An experimental investigation on the mechanical mechanisms of fatigue-crack initiation and propagation of a nickel-based superalloy is presented. By coupling digital image correlation method and scanning electron microscope, the fatigue residual strain distribution at the grain scale has been obtained. showed that there is a trend of accumulation for the residual strain. Micro-cracks are more likely to orbit the areas with particularly large residual strain, and propagate along the large-strain paths.