The　Electrophoretic　deposition　grain　boundary　diffusion　(EPD-GBD)　technology　for　sintered　Nd-Fe-B　magnets　has　garnered　significant　attention.　In　this　study,　TbF3　3　nano-powders　were　synthesized　via　sand　milling　(SM)　process,　and　the　optimal　processes　were　subsequently　explored.　Notably,　the　SM　powders　exhibit　two　morphologies:　blocky　and　flocculent.　With　prolonged　SM　time,　the　proportion　of　larger　blocky　powders　decreases　gradually,　while　the　proportion　of　smaller　flocculent　powders　increases.　The　morphology　and　proportion　of　the　powders　significantly　impact　the　EPD　rate　and　the　effectiveness　of　GBD.　Higher　blocky　powders　proportion　improved　diffusion,　reducing　residual　Tb　layer　and　enhancing　magnet　coercivity.　Higher　flocculent　powders　proportion　caused　cracking,　poor　diffusion,　thicker　residual　layer,　and　lower　coercivity.　However,　a　high　EPD　rate　was　achieved　with　a　high　proportion　of　flocculent　powders.　Considering　both　EPD　rate　and　diffusion　effect,　the　SM　process　at　1500　r/min　for　30　minutes　was　identified　as　the　optimal　parameter.　The　TbF3　3　nano-powders　prepared　by　these　conditions　exhibited　superior　advantage　in　the　EPD　process　and　the　coercivity　of　GBD　magnets　compared　to　traditional　micron-scale　TbF3　3　powders,　demonstrating　the　benefits　of　the　SM　process　in　the　EPD　and　GBD　processes　of　Nd-Fe-B　magnets.