Performance　and　fatigue　life　of　coating　parts　are　seriously　restricted　by　their　interfacial　fatigue　property.　Herein,　TiN　films　were　deposited　on　W6Mo5Cr4V2　steel　substrates　by　multiarc　ion　plating.　The　interfacial　fatigue　failure　mechanisms　were　studied　by　the　rolling　contact　fatigue　method.　The　results　show　that　the　interfacial　fatigue　failure　mode　is　mainly　film　spalling.　The　fatigue　cracks　generated　initially　at　the　film/substrate　interface　proceed　to　the　surface,　resulting　in　film　spalling.　The　interfacial　maximum　shear　stress　amplitude　(Delta　tau(inter))　is　a　key　factor　for　controlling　interfacial　crack　initiation　and　propagation.　The　evolution　model　built　using　Delta　tau(inter)　and　critical　cycles　(N)　can　be　used　to　determine　interfacial　fatigue　performance　and　for　life　forecast.　The　interfacial　fatigue　property　is　determined　using　a　film/substrate　interface,　and　glow　discharge　cleaning　and　prefabricated　metal　layer　before　coating　deposition　can　improve　interface　fatigue　performance.　The　evaluation　model　based　on　Delta　tau(inter)-N　curves　can　effectively　used　to　identify　the　differences　in　interface　states.　Selection　of　the　film-spalling　area　ratios　of　5%　and　50%　and　failure　probabilities　of　30%,　60%,　and　90%　have　little　effect　on　the　determination　of　film/substrate　interfacial　fatigue　performance.　The　results　provide　important　theoretical　references　for　fatigue　performance　determination　and　lifespan　prediction　of　coated　bearings　and　other　parts.