The　grinding　sludge　of　grain　boundary　diffusion　Nd-Fe-B　magnet　is　rich　in　heavy　rare　earth　and　has　a　typical　core–shell　microstructure.　In　this　work,　an　ultra-short　process　was　developed　to　realize　green,　in-situ　regeneration　of　the　sludge　and　efficient　reuse　of　heavy　rare　earth　elements.　The　regenerated　magnets　showed　excellent　magnetic　performance　and　good　temperature　stability　which　were　fabricated　after　the　purification　of　sludge,　composition　regulation　with　rare　earth-rich　compounds,　Nd42.1FebalB0.79,　NdHx,　(PrNd)Hx,　and　sintering.　Especially,　the　magnet　prepared　by　using　Nd42.1FebalB0.79　alloy　had　significant　property　recovery,　where　remanence　and　coercivity　were　restored　to　12.8　kG,　and　20.6　kOe,　respectively,　reaching　97.7　%　and　162.5　%　of　the　original　magnet.　The　magnetization　reversal　behavior　and　the　coercivity　mechanism　were　analyzed　to　keep　the　nucleation　mechanism,　and　the　high　coercivity　stemmed　from　the　repair　and　optimization　of　the　grain　boundary　by　introducing　rare　earth-rich　alloys,　the　full　utilization　of　heavy　rare　earth　elements,　and　the　core–shell　microstructure　rooted　in　the　sludge　as　well.　©　2024