In　this　paper,　an　ultra-high-strength,　fine-grained　NbMoTaTiNi　high-entropy　alloy　was　formed　by　SLM(se-lective　laser　melting).　The　compressive　yield　strength　at　room　temperature　can　reach　1728Mpa,　the　ultimate　strength　is　as　high　as　2753　MPa,　the　strain　is　21.75　%,　and　the　tensile　strength　is　1205Mpa.　The　as-cast　alloys　were　annealed　at　600　degrees　C,　800　degrees　C,　1000　degrees　C,　1200　degrees　C,　and　1300　degrees　C　to　study　their　microstructure　and　mechanical　properties.　After　annealing　at　1200　degrees　C,　the　compressive　plasticity　of　the　alloy　is　as　high　as　33.55　%,　an　increase　of　54.3　%.　With　the　increase　of　annealing　temperature,　the　alloy　gradually　transforms　from　den-drites　to　cellular　crystals,　and　the　XB　phase,　which　is　the　grain　boundary　phase　resists　thermal　stress　crack　defects　through　stacking　faults.　The　calculation　of　alloy　stability　parameters　shows　that　the　alloy　forms　a　disordered　(matrix　phase)-transition　(XB　grain　boundary　phase)-ordered　(B2　grain　boundary　phase)　structure,　and　with　the　increase　of　annealing　temperature,　the　lattice　distortion　of　the　matrix　phase　de-creases.　The　matrix　phase　tends　to　be　more　disordered　and　stable.　The　lattice　distortion　of　the　B2　phase　increases　and　the　B2　phase　tends　to　be　more　ordered　and　stable,　and　the　XB　phase　increases　the　stability　of　the　disorder-ordered　phase　boundary　of　the　alloy.　In　this　paper,　through　the　research　on　the　annealing　process　of　NbMoTaTiNi　high-entropy　alloy,　the　plasticity　of　NbMoTaTiNi　high-entropy　alloy　is　improved,　and　the　engineering　application　of　NbMoTaTiNi　high-entropy　alloy　in　aerospace,　nuclear　energy　and　other　fields　is　proposed.(c)　2023　Published　by　Elsevier　B.V.