The　structure　and　phase　modification　of　sintered　Nd-Fe-B　magnets　through　Tb　diffusion　from　two　different　sources,　nano　TbHx　and　TbF3　particles,　and　their　effects　on　magnetic　and　corrosion-resistant　properties,　were　investigated.　The　results　demonstrate　that　Tb　diffusion　from　TbHx　leads　to　an　optimized　microstructure　with　fewer　anti-core-shell　grains,　a　longer　diffusion　distance,　and　better　magnetic　isolation　than　TbF3.　In　contrast,　TbF3　facilitates　Tb　diffusion　into　the　main　phase　and　also　blocks　its　diffusion　channels　in　the　grain　boundaries,　resulting　in　accumulation　at　the　surface　and　significantly　reducing　the　diffusion　efficiency　of　the　Tb　element.　Additionally,　the　study　reveals　a　key　role　of　Tb　in　influencing　the　electrode　potential　of　different　phases　and,　consequently,　the　corrosion　behavior　of　Nd-Fe-B　magnets.　Tb　diffusion　slightly　increases　the　electrode　potential　of　the　shell　of　main　phase　grains　while　significantly　increasing　that　of　the　Nd-O　phase.　It　thus　reduces　the　interphase　potential　difference　thereby　enhancing　the　corrosion　resistance　of　the　magnets.　However,　when　TbF3　is　used　for　diffusion,　the　formation　of　a　new　(Nd,　Tb)-O-F　phase,　which　exhibits　significantly　lower　potential　than　the　(Nd,　Tb)-O　phase,　leads　to　a　deterioration　in　corrosion　resistance.　These　findings　provide　valuable　insights　into　the　magnetic　and　corrosion　behaviors　of　grain　boundary　diffusion　magnets　and　highlight　key　factors　for　developing　advanced　permanent　magnets　with　enhanced　overall　performance.