Microstructure　and　magnetic　properties　were　studied　for　the　commercial　Sm(CoFeCuZr)z　magnets　before　and　after　post　annealing　treatment.　The　results　show　that　the　phases　composition　and　orientation　of　the　magnet　do　not　change　after　post　annealing　treatment,　but　the　substantial　redistribution　of　Cu　element　within　multiscale　(the　microscale　crystal　grain　and　the　nanoscale　cellular　structure)　is　observed　simul-taneously.　In　detail,　along　with　the　Cu　redistribution,　the　thickness　of　the　Cu-rich　Sm(Co,Cu)5　cell　boundary　becomes　thinner,　and　the　Cu　concentration　in　the　boundary　increases　sharply.　The　pinning　field　of　domain　walls　and　corresponding　coercivity　increase　remarkably　with　slight　remanence　and　maximum　energy　product　loss,　and　the　overall　magnetic　performance　of　(BH)max　(MGOe)　thorn　Hcj　(kOe)　increases　by　54.3%　as　a　result.　Moreover,　the　thermal　stability　of　the　magnet　improves　as　well.　On　the　other　hand,　Cu-lean　phenomenon　was　observed　along　the　grain　boundary　region,　triggering　to　magnetic　domain　reversal　process　and　slightly　undermining　the　squareness　of　the　demagnetization　curve　of　the　magnet.(c)　2021　Chinese　Society　of　Rare　Earths.　Published　by　Elsevier　B.V.　All　rights　reserved.