The　effects　of　different　curing　regimes　on　the　performance　of　ultra-high　performance　concrete　containing　metakaolin　and　magnesium　oxide　(MM-UHPC)　were　investigated.　Four　curing　regimes　were　included,　namely　standard　curing　(SC),　hot　water　curing　(HC),　steam　curing　(MC),　and　autoclave　curing　(AC).　Additionally,　the　hydration　products,　pore　structure,　microhardness,　interfacial　transition　zone　(ITZ)　properties,　and　single　fiber　pullout　properties　of　MM-UHPC　were　characterized　to　reveal　the　influencing　mechanism.　The　results　showed　that　compared　to　SC,　the　thermal　curing　(HC,　MC,　and　AC)　facilitated　the　incorporation　of　Al　elements　from　metakaolin　into　hydrated　calcium　silicate　(C-S-H),　increasing　the　average　chain　length　of　C-S-H　and　promoting　the　crosslinking　of　long　straight　silicate　chains.　The　thermal　curing　also　promoted　the　secondary　hydration　reaction　of　calcium　hydroxide　[Ca(OH)(2)]　enriched　in　the　ITZ,　improving　the　ITZ　properties,　increasing　the　microhardness　value　of　the　ITZ,　and　enhancing　the　friction　force　between　steel　fibers　and　matrix.　Furthermore,　the　thermal　curing　reduced　the　porosity　of　matrix　and　refined　the　pore　structure　of　matrix.　These　factors　resulted　in　an　increase　in　120　days　flexural　strength　of　MM-UHPC　by　14.9　%,　10.5　%,　and　20.9　%　for　HC,　MC,　and　AC,　respectively,　compared　to　SC.　Similarly,　the　compressive　strength　increased　by　12.0　%,　11.4　%,　and　24.9　%,　respectively.　The　120　days　flexural　and　compressive　strength　of　MM-UHPC　are　in　the　following　order:　AC　＞　HC　＞　MC　＞　SC.