The　damping　property　and　mechanisms　of　ultra-high　performance　concrete　(UHPC)　were　experimentally　investigated　considering　factors　such　as　steel　fiber　parameters　and　curing　regimes.　The　results　showed　that　incorporating　steel　fibers　enhances　the　damping　capacity　of　UHPC,　with　a　54.　9%　increase　in　damping　ratio　achieved　at　2.　5%　steel　fiber　volume　content　compared　to　UHPC　without　steel　fibers.　Reducing　the　aspect　ratio　of　steel　fibers　and　adopting　standard　curing　were　found　to　improve　the　damping　property　of　UHPC.　Proper　selection　of　steel　fiber　parameters　and　curing　regimes　enables　the　production　of　UHPC　materials　that　balance　damping　capacity,　mechanical　strength,　and　economic　efficiency.　Considering　both　positive　and　negative　effects　of　steel　fibers　on　the　damping　property　of　UHPC,　a　semi-empirical　predictive　formula　for　UHPC　material　damping　was　established.　At　the　microstructural　level,　increasing　steel　fiber　content,　reducing　aspect　ratio,　and　applying　standard　curing　led　to　promote　the　formation　of　internal　defects　in　the　UPHC　matrix　including　fiber-matrix　interface　transition　zones,　micropores,　and　microcracks.　These　microstructural　characteristics　facilitate　energy　dissipation　through　multiple　mechanisms,　including　deformation　of　steel　fibers,　interfacial　friction　between　steel　fibers　and　matrix,　opening　and　closing　of　microcracks,　distortion　of　micropores,　and　flexible　cushioning　effects　from　air　within　micropores,　which　contribute　to　enhanced　damping　capacity　of　steel-fiber　reinforced　UHPC.　©　2025　Chinese　Vibration　Engineering　Society.　All　rights　reserved.