The　initiation　and　propagation　of　fatigue　cracks　from　notches　have　been　studied　in　a　high　strength　aluminum　alloy　7010-T736.　The　experimental　results　suggest　that　a　modified　effective　stress　intensity　factor,　which　is　described　by　introducing　a　function　of　microstructure　scale,　notch　geometry　and　short　crack　length,　is　applicable　to　predict　initiation　of　fatigue　crack　emanating　from　notches　and　fatigue　crack　propagation　within　the　notch　stress　field.