The　structure　and　magnetic　properties　were　studied　for　bulk　nanocrystalline　SmCo5　sintered　magnet　produced　by　spark　plasma　sintering　technique.　X-ray　diffraction　patterns　show　that　the　sintered　magnet　exhibits　CaCu5　crystal　structures.　Transmission　electron　microscopy　(TEM)　observation　indicates　the　average　grain　size　of　the　magnet　of　about　40　nm.　Magnetic　measurement　shows　that　the　coercivity　reaches　as　high　as　2.85　T;　the　saturation　magnetization　and　the　remanence　are　0.71　and　0.5　T,　respectively.　The　magnet　exhibits　good　thermal　stability　with　a　coercivity　of　0.9　T　at　773　K　and　a　coercivity　coefficient　beta　of　-0.15%/K.　(C)　2010　American　Institute　of　Physics.　[doi:　10.1063/1.3334458]