Sm-Co　alloys　are　the　most　promising　candidates　for　high　temperature　applications　in　advanced　power　systems　owing　to　their　high　Curie　temperature　and　high　thermal　stability　of　the　magnetic　performance.　The　recently　developed　nanocrystalline　Sm-Co　based　magnets　exhibit　great　potentials　for　magnetic　performance　enhancement　and　are　expected　to　enlarge　applications　to　services　under　extreme　conditions.　However,　there　have　been　few　comprehensive　reviews　on　the　development　of　the　nanocrystalline　Sm-Co　magnets　so　far.　The　efforts　in　this　article　are　paid　to　review　the　recent　progress　in　both　experimental　and　modeling　studies　on　the　nanocrystalline　Sm-Co　magnets.　Particularly,　the　latest　advances　in　nanostructuring　technologies,　doping　modulation,　data-driven　composition　design　and　strategies　for　enhancement　of　magnetic　properties　have　been　introduced　and　evaluated.　Finally,　new　challenges　and　opportunities　regarding　the　future　development　of　high-performance　nanocrystalline　Sm-Co　based　magnets　are　proposed.　(C)　2022　Elsevier　Ltd.　All　rights　reserved.