The　hot-deformed　(HD)　Nd-Fe-B　magnets　show　heterogeneous　microstructure　composed　of　coarse　and　fine　grain　regions.　It　is　significant　to　fully　understand　the　influence　of　this　complex　microstructure　on　the　magnetization　reversal　process　which　can　give　the　guidance　for　the　enhancement　of　the　magnetic　properties.　In　this　paper,　the　heterogeneous　microstructure　of　the　(HD)　Nd-Fe-B　magnets　were　characterized　from　the　morphology,　size,　macro-texture　and　micro-structure.　In　addition,　the　magnetization　reversal　process　of　the　HD　Nd-Fe-B　magnets　was　systematically　analyzed　by　magnetic　measurement,　in-situ　domain　evolution　observation　and　micromagnetic　simulation.　The　results　indicate　that　the　HD　NdFe-B　magnets　mainly　consist　of　fine　grain　regions　(FGRs)　and　coarse　grain　regions　(CGRs).　The　FGRs　show　plate-like　grains　with　fine　grain　size　and　strong　c-axis　texture,　while　the　CGRs　show　equiaxial　grains　with　large　grain　size　and　weak　c-axis　texture.　In　particular,　it　is　worth　noting　that　the　texture　in　homogeneity　exists　not　only　between　FGRs　and　CGRs,　but　also　inside　both　the　FGRs　and　CGRs.　The　dominant　coercivity　mechanism　of　the　HD　Nd-Fe-B　magnets　is　domain　wall　pinning.　Also,　the　experimental　analysis　shows　that　the　reverse　domain　is　formed　and　expanded　in　the　CGRs　at　low　reverse　applied　field,　while　the　reverse　domain　occurs　in　the　FGRs　at　higher　reverse　applied　field.　The　micromagnetic　simulation　results　also　confirm　the　above　magnetization　reversal　process.　In　addition,　micromagnetic　simulation　results　also　show　that　the　orientation　of　the　grains　also　affects　the　pinning　strength,　besides　the　grain　size.　(C)　2019　Chinese　Society　of　Rare　Earths.　Published　by　Elsevier　B.V.　All　rights　reserved.