Railway　axles　with　inside　axle　boxes　have　a　great　potential　in　modern　urban　railway　system　due　to　good　dynamic　performance　on　small-radius　track.　However,　because　of　entirely　different　loading　nature　from　widely-used　one,　a　challenging　problem　of　the　fatigue　performance　and　damage　endurance　arises　in　the　case　of　defects　from　various　external　sources.　In　this　paper,　a　stepwise　fatigue　assessment　framework　composed　of　safe　life　as　the　first　level　and　damage　tolerance　as　the　second　level　was　tentatively　proposed　for　the　wheelset　with　inside　axle　boxes.　An　assumed　load　spectrum　was　employed　to　estimate　the　remaining　life　for　a　damaged　axle　made　of　the　EA4T　steel.　Calculated　results　show　that　the　critical　safety　region　has　been　transferred　to　the　axle　center　in　contrast　to　classical　axles,　where　a　1.0　mm-depth　crack　as　the　inspection　limit　has　less　probability　to　propagate.　Besides,　the　wheelset　with　inside　axle　boxes　shows　the　smaller　stress　value.　The　analysis　from　well-known　Kitagawa-Takahashi　diagram　indicates　a　security　risk　while　only　using　nominal　stress　approach.