This　work　was　focused　on　the　effects　of　Mn　doping　on　the　phase　stability　and　magnetic　performance　of　SmCo7　based　alloys.　Particularly,　the　role　of　Mn　in　the　improvement　of　the　magnetization　of　the　SmCo7　matrix,　as　well　as　its　mechanisms,　was　examined　in　detail.　The　metastable　SmCo7　single　phase　was　well　stabilized　by　the　appropriate　content　of　Mn　doping　and　nanostructuring　of　the　alloy.　It　was　discovered　that　the　non-ferromagnetic　element　Mn　can　enhance　magnetization　effectively.　By　tailoring　the　Mn　content　and　nanostructuring,　the　prepared　SmCo7-xMnx　alloy　achieved　good　comprehensive　magnetic　properties.　The　mechanisms　for　the　magnetization　enhancement　by　Mn　and　the　coupled　effect　of　Mn　doping　and　nanostructuring　on　the　magnetic　properties　were　proposed　based　on　the　characterization　of　magnetic　structures　and　the　model　calculations　of　magnetic　moments.