In　this　paper,　a　1　MW　supercritical　carbon　dioxide(SCO2)radial　inflow　turbine　is　designed　to　meet　the　requirement　of　a　MW-class　SCO2　Brayton　cycle　system.　The　three-dimensional　numerical　simulation　is　carried　out　by　RANS(Reynolds-averaged　Navier-Stokes)equations.　The　off-design　performance　of　the　turbine　is　analyzed　and　the　influence　of　the　tip　clearance　on　the　efficiency　is　also　investigated.　The　operation　safety　of　the　turbine　impeller　is　analyzed　with　the　thermal-fluid-structure　coupling　method.　Based　on　the　numerical　simulation　results　and　actual　operating　conditions　of　the　turbine　impeller,　the　corresponding　thermal　load　and　aerodynamic　load　were　applied　in　this　process.　The　axial　force　caused　by　the　leakage　flow　at　the　backface　cavity　of　impeller　is　also　considered.　The　results　show　that　the　isentropic　efficiency　and　the　output　power　of　turbine　under　design　conditions　are　83.53%　and　1　188.57　kW,　respectively.　The　SCO2　turbine　exhibits　good　off-design　performance.　The　maximum　total　deformation　of　the　turbine　impeller　made　of　titanium　alloy　TC4　is　0.570　mm　while　the　maximum　axial　deformation　is　0.303　mm.　The　stress　of　the　impeller　is　far　smaller　than　the　material　yield　strength.　The　research　results　can　provide　basic　data　and　theoretical　support　for　the　turbine　design　of　MW-class　SCO2　Brayton　cycle　system.　©　2022　Xi＇an　Jiaotong　University.　All　rights　reserved.