A　new　type　of　Sm-Co　supersaturated　solid　solution　has　been　developed　with　a　stabilized　TbCu7-type　structure.　The　high-Co　single　phases　were　stabilized　in　a　wide　temperature　range　in　the　prepared　SmCo9.8-x　Si　(x)　(x=0-0.9)　alloys　by　concurrent　nanostructuring　and　Si-doping.　The　significant　enhancement　of　the　coercivity　and　remanence　of　the　new　type　supersaturated　solid　solution　are　attributed　to　the　effective　pinning　of　the　ultrafine　nanograin　boundaries　and　the　high　magnetocrystalline　anisotropy　of　the　solid　solution.　It　was　proposed　that　the　high-temperature　magnetic　properties　of　the　Sm-Co　supersaturated　solid　solution　depend　strongly　on　the　phase　stability.