In　order　to　research　the　safe　life　of　the　train　wheel　structure,　in　this　paper,　the　fatigue　limit　of　the　train　wheel＇　steel　was　measured　by　the　up　and　down　method,　and　the　grouping　method　during　moderate　and　short　life.　The　fatigue　performance　of　smooth　specimens　made　of　the　train　wheel＇　steel　was　tested,　the　relational　expression　of　stress　amplitude　and　fatigue　life　was　set　up　by　means　of　index　S-N　curve　equations,　and　P-S-N　curve　under　different　reliability　(90%,　99%)　was　established.　This　expression　can　be　regarded　as　the　basis　for　estimating　fatigue　life　and　fatigue　reliability　based　design.