The　centrifugal　compressor　is　the　key　component　to　improve　the　SCO2　cycle　efficiency.　In　this　paper,　according　to　150kW　class　supercritical　carbon　dioxide　(SCO2)　simple　Brayton　cycle,　a　centrifugal　compressor　with　rotating　speed　60000r/min　is　designed.　For　the　small-scale　SCO2　centrifugal　compressor,　the　impeller　tip　clearance　loss　accounts　for　most　of　the　aerodynamic　loss.　Therefore,　the　designed　compressor　performance　is　numerically　studied　by　the　three-dimensional　Reynolds-Averaged　Navier-Stokes　(RANS)　and　k-Ε　(Extended　Wall　Function)　turbulence　model.　The　large　variations　in　physical　properties　for　SCO2　near　the　critical　make　simulation　be　difficult　to　convergence.　To　keep　the　numerical　stability　and　accuracy,　400×400　resolution　physical　properties　tables　are　adopted　by　the　physical　properties　tables　verification.　The　designed　SCO2　centrifugal　compressor　is　with　the　isentropic　efficiency　of　73.2%　and　the　pressure　ratio　of　2.207　under　the　design　flow　condition,　and　good　off-design　conditions　performance　are　obtained.　Compared　to　the　flow　condition　without　the　impeller　tip　clearance,　the　isentropic　efficiency　of　designed　compressor　decreases　by　14%.　For　the　impeller　tip　clearance　leakage　flow,　the　flow　can　be　divided　into　three　regions,　the　separation　flow　region　which　is　along　the　mainstream　flow　direction,　the　back　flow　region　which　occupies　the　top　of　the　impeller　tip　clearance　and　the　downstream　flow　region　which　occupies　the　bottom　of　the　impeller　tip　clearance.　These　flow　phenomena　and　their　causes　are　analyzed.　The　obtained　results　reveal　that　the　designed　centrifugal　compressor　meets　the　requirement　of　the　aerodynamic　performance　for　the　150kW　class　simple　Brayton　cycle.　The　detailed　flow　pattern　of　the　designed　SCO2　centrifugal　compressor　with　consideration　of　the　impeller　tip　leakage　flow　is　also　illustrated.　Copyright　©　2020　ASME