Dielectric　materials　with　colossal　permittivity　(CP,　Εr　＞　104)　have　attracted　the　increasing　interest　of　researchers　due　to　their　enormous　potential　in　the　fields　of　sensor,　capacitor,　energy　storage,　etc.　However,　for　the　explored　CP　materials,　their　grains　are　too　large　to　apply.　To　control　grain　growth,　the　sintering　aids　of　MgO–Al2O3–SiO2　(MAS)　cordierite　glass　and　common　suppression　grain　growth　of　MgO　have　been　introduced　to　BaTiO3-0.004Y2O3-0.006MnO2　ceramics　derived　from　the　commercial　BaTiO3　powder　with　the　average　grain　size　of　300　nm.　After　controlling　grain　growth,　the　fine　grains　with　the　average　grain　size　of　dg　∼300　nm　and　CP　are　achieved　in　BaTiO3　based　ceramics　sintered　in　reducing　atmosphere.　Notably,　excellent　temperature　stability　with　ΔΕr/Εr25°C　lower　than　17　%　is　gained　for　the　present　BaTiO3　based　ceramics　in　the　temperature　range　of　−60　to　155　°C,　meeting　the　X8S　specification　(ΔC/C25°C　≤±22　%,　−55　°C–150　°C).　Based　on　the　X-ray　photoelectron　spectroscopy　(XPS)　and　Raman　spectra,　the　outstanding　dielectric　properties　of　the　present　BaTiO3　based　ceramics　is　ascribed　to　the　electron-pinned　defect-dipole　(EPDD)　effect　induced　by　YTi′−YBa∙,　TiTi′−Vo∙∙−TiTi′　and　YTi′−Vo∙∙−TiTi′　defect　dipoles.　The　present　BaTiO3　based　fine　ceramics　with　colossal　permittivity　(∼2.9　×　104),　low　loss　(∼0.03)　at　1　kHz　and　room　temperature,　excellent　temperature　stability　and　high　resistivity　of　3.54　×　109　Ω　cm　is　a　promising　candidate　for　the　multilayer　ceramics　capacitor　(MLCC).　©　2024　Elsevier　Ltd　and　Techna　Group　S.r.l.