In　this　paper,　the　design　parameters　and　fatigue　loading　parameters　of　pre-stressed　concrete　box　girder　are　introduced,　and　the　multi-stage　variable　amplitude　fatigue　test　is　carried　out.　The　finite　element　model　of　pre-stressed　concrete　box　girder　is　established　by　using　ANSYS　finite　element　software.　Comparing　the　test　results　and　simulation　results,　it　is　found　that　the　load-deflection　curve　of　N=2　million　times　are　in　good　agreement.　The　principle　of　the　whole　fatigue　process　analysis　method　is　introduced.　On　this　basis,　the　cumulative　damage　under　different　fatigue　times　is　obtained.　The　fatigue　reliability　analysis　and　sensitivity　analysis　of　random　variables　are　carried　out　by　using　the　PDS　module　in　ANSYS.　©　2020　IOP　Publishing　Ltd.　All　rights　reserved.