Shrinkage　of　ultra-high　performance　concrete　(UHPC)　was　investigated　by　restrained　ring　tests　taking　the　restraint　degree,　sealed　or　dry　circumferential　condition　and　steel　fiber　as　the　main　parameters.　The　development　of　steel　ring　strain　with　age　was　studied.　The　influences　of　various　parameters　on　the　residual　stress　under　the　restrained　ring　and　the　mechanical　property　at　key　age　were　analyzed.　The　tensile　stress　level　and　the　relaxation　rate　were　used　to　evaluate　the　cracking　performance　of　UHPC.　Free　shrinkage　and　mechanical　properties　were　also　investigated　to　match　the　restrained　ring　test.　The　results　showed　a　high　early　cracking　risk　of　UHPC　without　steel　fiber.　All　specimens　cracked　with　an　average　width　of　more　than　0.25　mm　before　14　d,　while　the　specimens　with　steel　fiber　did　not　crack.　Various　restraint　degrees　all　have　significant　effects　on　both　the　tensile　stress　level　and　stress　relaxation　rate,　indicating　that　decreasing　the　restraint　degree　can　reduce　the　cracking　risk　effectively.　Different　from　the　free　shrinkage　test　results,　UHPC　under　ring　restraint　showed　higher　cracking　risk　at　the　late　stage　in　a　sealed　condition　than　in　a　dry　circumferential　condition.　The　crack　resistance　at　14　d　under　a　sealed　condition　is　recommended　as　a　control　index　to　evaluate　the　cracking　performance　of　UHPC　under　restrained　ring.　©　2019,　Engineering　Mechanics　Press.　All　right　reserved.