From　the　viewpoint　of　dynamics,　the　nature　of　the　fatigue　failure　of　a　centrifugal　impeller　is　presented.　By　using　finite　element　method　and　mode　analysis,　the　dynamics　of　the　centrifugal　impeller　is　studied　numerically.　It　is　found　that　centrifugal　impeller　is　the　typical　periodic　structures,　and　there　exist　many　unique　dynamics　in　comparison　to　non-periodic　structures,　such　as　the　vibration　localization,　passbands　and　stopbands.　The　amplitude　and　the　resulting　energy　will　be　uniform　in　the　structure　as　the　exciting　force　in　the　range　of　passbands.　On　the　other　hand,　the　amplitude　and　the　resulting　energy　will　be　limited　at　local　part,　and　the　amplitude　and　stress　will　be　increased　greatly,　the　centrifugal　impeller　will　be　destroyed　as　the　energy　is　localized.　Additionally,　influences　of　mistuning　from　the　manufacture　process,　material　and　wear　on　the　dynamics　of　the　system　are　significant.　For　some　cases,　such　as　the　structure　with　dense　modes,　small　mistuning　(1%)　will　lead　to　great　change　of　the　mode,　result　in　vibration　localization.　For　the　centrifugal　impeller　studied,　the　numerical　results　show　that　the　inlet　portions　of　blades　behave　with　large　amplitude　and　train,　as　the　exciting　frequency　(1166.7Hz)　from　inlet　guide　vane　is　close　to　the　stopband　(1020.3　Hz　-1054.5　Hz)　of　centrifugal　impeller,　and　it　agrees　well　with　the　broken　centrifugal　impeller.　As　a　conclusion,　it　can　be　drawn　that　such　mode　localization　is　the　key　to　the　fatigue　failure　of　the　centrifugal　impeller　and　such　fatigue　failure　results　from　resonance.