Nanocomposite　permanent　magnets　have　ultra-high　theoretical　magnetic　energy　products,　due　to　cou-pling　of　the　soft/hard　magnetic　phases,　inciting　strict　microstructural　requirements.　In　this　study,　the　microstructure　evolution,　including　the　phase　transition,　morphological　changes,　and　texture　formation,　of　hot-deformed　SmCo-based　nanocomposites　under　thermal-stress-strain　coupling　was　characterized　to　determine　a　possible　strategy　for　achieving　high　performance.　The　SmCo5/alpha-Fe　nanocomposites　precursor　contained　fine　and　dispersed　Sm(Fe,　Co)5　and　Fe-Co　grains　and　exhibited　a　two-stage　phase　transforma-tion　accompanied　by　grain　growth.　In　the　early　stage　of　deformation　at　relatively　low　temperature,　the　adjacent　Sm(Co,　Fe)5　and　Fe-Co　phase　formed　the　Sm2(Co,　Fe)17-H　phase,　which　was　stable　only　with　small　grain　sizes.　In　the　high-temperature　deformation　stage,　the　Sm2(Co,　Fe)17-H　phase　transformed　into　the　Sm2(Co,　Fe)17-R　phase　with　large　grain　sizes.　In　addition,　the　strong　c-axis　texture　formed　in　the　Sm(Co,　Fe)5　phase　but　not　in　the　Sm2(Co,　Fe)17-R　phase.　Subsequently,　the　phase　transition　process　and　texture　formation　mechanism　were　systematically　analyzed　by　transmission　electron　microscopy.　The　ini-tiation　of　a　slip　system　and/or　preferential　grain　growth　explained　the　formation　of　texture　under　the　action　of　uniform　stress　and　strain　and　assisted　by　dispersed　Sm-rich　nanograins.　The　Sm2(Co,　Fe)17-R　grains　with　poor　orientations　and　large　grain　sizes　did　not　achieve　magnetic　hardening,　which　also　dam-age　the　magnetic　properties.　According　to　the　results　of　this　work,　we　also　presented　a　new　strategy　to　prepare　high-performance　SmCo-based　nanocomposites　magnets.(c)　2022　Published　by　Elsevier　Ltd　on　behalf　of　The　editorial　office　of　Journal　of　Materials　Science　&　Technology.