Based　on　a　home-built　Sm-Co-based　alloys　database,　this　work　proposes　a　support　vector　machine　model　to　study　the　concurrent　effects　of　element　doping　and　microstructure　scale　on　the　phase　constitution　of　SmCo7-based　alloys.　The　results　indicated　that　the　doping　element＇s　melting　point　and　electronegativity　difference　with　Co　are　the　key　features　that　affect　the　stability　of　the　1:7　H　phase.　High-throughput　predictions　on　the　phase　constitution　of　SmCo7-based　alloys　with　various　characteristics　were　achieved.　It　was　found　that　doping　elements　with　electronegativity　differences　with　Co　that　are　smaller　than　0.05　can　significantly　enhance　1:7　H　phase　stability　in　a　broad　range　of　grain　sizes.　When　the　electronegativity　difference　increases　to　0.4,　the　phase　stability　becomes　more　dependent　on　the　melting　point　of　the　doping　element,　the　doping　concentration,　and　the　mean　grain　size　of　the　alloy.　The　present　data-driven　method　and　the　proposed　rule　for　1:7　H　phase　stabilization　were　confirmed　by　experiments.　This　work　provides　a　quantitative　strategy　for　composition　design　and　tailoring　grain　size　to　achieve　high　stability　of　the　1:7　H　phase　in　Sm-Co-based　permanent　magnets.　The　present　method　is　applicable　for　evaluating　the　phase　stability　of　a　wide　range　of　metastable　alloys.