The　regeneration　of　Nd-Fe-B　sludge　is　of　great　practical　significance　for　achieving　the　sustainable　development　and　recycling　of　rare　earth　elements.　In　this　study,　the　in-situ　regeneration　of　sludge　was　realized　at　a　lower　temperature　of　850　degrees　C　via　the　mechanochemical　approach　based　on　ball-milling　and　Ca-reduction　diffusion.　Single-phase　nanocrystalline　magnetic　powders　with　high　coercivity　were　prepared　by　regulating　the　experimental　parameters　and　rare　earth　elements.　The　grain　size　of　Nd-Fe-B　powder　obtained　by　5　wt%　TbHx　addition　was　68.1　nm,　with　a　high　coercivity　of　18.38　kOe.　After　purification　and　dehydrogenation,　the　coercivity　was　6.68　kOe,　and　the　coercivity　mechanism　was　controlled　by　reverse　magnetic　domain　nucleation.　The　low　temperature　in　this　study　significantly　reduced　the　energy　consumption　for　the　calcium　reduction　regeneration　of　sludge.　It　facilitated　the　preparation　of　nanocrystalline　Nd-Fe-B　powders　with　high　coercivity,　offering　a　new　idea　for　recycling　Nd-Fe-B　sludge.