The　microstructure　of　(Nd,　Ce)–Fe–B　sintered　magnets　with　different　diffusion　depths　was　characterized　by　a　magnetic　force　microscope,　and　the　relationship　between　the　magnetic　properties　and　the　local　structure　of　grain　boundary　diffused　magnets　is　discussed.　The　domains　perpendicular　to　the　c-axis　(easy　magnetization　direction)　show　a　typical　maze-like　pattern,　while　those　parallel　to　the　c-axis　show　the　characteristics　of　plate　domains.　The　significant　gradient　change　is　shown　in　the　concentration　of　Dy　with　the　direction　of　diffusion　from　the　surface　to　the　interior.　Dy　diffuses　along　grain　boundaries　and　(Dy,　Nd)2Fe14B　layer　with　a　high　anisotropy　field　formed　around　the　grains.　Through　in-situ　electron　probe　micro-analysis/magnetic　force　microscopy　(EPMA/MFM),　it　is　found　that　the　average　domain　width　decreases,　and　the　proportion　of　single　domain　grains　increases　as　diffusion　depth　increases.　This　is　caused　by　both　the　change　of　concentration　and　distribution　of　Dy.　The　grain　boundary　diffusion　process　changes　the　microstructure　and　microchemistry　inside　the　magnet,　and　these　local　magnetism　differences　can　be　reflected　by　the　configuration　of　the　magnetic　domain　structure.　©　2024　Chinese　Society　of　Rare　Earths