In　this　study,　to　clarify　the　failure　mechanism　of　the　last-stage　rotor　blade　in　the　low-pressure　cylinder　of　a　steam　turbine,　the　peculiarities　of　crack　initiation　and　propagation　on　the　inlet　side　of　the　last-stage　rotor　blade　at　a　distance　of　125-165　mm　were　analyzed,　along　with　the　corrosion　fatigue　properties　of　its　materials.　The　results　showed　that　crack　initiation　occurred　at　the　tip　of　the　pit　due　to　a　combination　of　factors:　stress　concentration　at　the　tip　of　the　pit,　corrosion　of　the　Cr-poor　area　near　the　prior　austenite　grain　boundary,　centrifugal　tensile　stress,　and　steam　bending　stress.　The　crack　propagation　could　be　divided　into　the　initial　intergranular　and　late　transgranular　propagation　stages.　The　main　reason　for　the　initial　intergranular　propagation　was　stress　corrosion,　and　the　main　reason　for　the　later　transgranular　propagation　was　corrosion　fatigue.　High-frequency　induction　quenching　technology　can　improve　the　microhardness　of　the　blade＇s　surface　material　and　enhance　the　blade＇s　resistance　to　water　erosion,　but　it　may　also　reduce　the　corrosion　fatigue　resistance　of　the　blade　material.　The　rotary　bending　corrosion　fatigue　test　can　effectively　simulate　the　crack　propagation　process　of　the　blade.　These　results　are　of　great　significance　for　the　safe　operation　of　the　last-stage　rotor　blade　in　the　lowpressure　cylinder　of　a　steam　turbine.