A　variety　of　intermetallic　compounds　in　the　binary　Sm-Co　system　were　reviewed,　and　the　contents　were　focused　on　the　crystal　structures,　magnetic　properties　and　the　nanoscale　effects.　The　representative　nanocrystalline　Sm-Co　compounds　were　introduced　in　details,　the　diagrams　for　their　lattice　structures　and　the　atomic　sites　and　occupancies　were　provided.　Moreover,　the　magnetic　properties　of　the　nanocrystalline　Sm-Co　compounds　were　compared　with　those　of　the　conventional　polycrystalline　counterparts.　It　showed　that　the　nanocrystalline　Sm-　Co　compounds　exhibit　special　phase　stability　and　remarkably　enhanced　magnetic　performance,　which　are　promising　candidates　for　the　matrix　phases　to　develop　permanent　magnets,　particularly　the　advanced　high-　temperature　magnetic　materials.