Sodium　niobate　(NaNbO3,　NN)-based　ferroelectric　ceramics　have　been　extensively　studied　owing　to　their　antiferroelectric　(AFE)　nature.　However,　the　dielectric　properties　of　NN-based　ceramics,　which　would　be　beneficial　to　capacitor　devices,　gain　less　research　interest.　In　this　study,　(1−x)NaNbO3-xBi(Mg0.5Ti0.5)O3　(NN-xBMT,　x　=　0,　0.01,　0.02,　0.03,　0.04,　0.05)　ferroelectric　ceramics　were　manufactured　by　a　traditional　solid　state　method.　Structure　and　dielectric/ferroelectric　properties　were　studied　in　detail　by　X-ray　diffraction,　dielectric　spectrum　as　well　as　polarization-electric　field　hysteresis　loops.　All　ceramic　samples　show　an　AFE　P　phase　in　the　doping　range.　As　x　increases,　the　grain　size　of　studied　compositions　gradually　decreases　from　5.36　μm　in　x　=　0　to　2.05　μm　in　x　=　0.05.　In　addition,　the　incorporation　of　BMT　plays　a　regulatory　role　to　the　Curie　temperature　TC　of　ceramic　samples,　which　decreases　almost　linearly　from　375　°C　x　=　0　to　216　°C　x　=　0.05　at　a　rate　of　33　°C/1　at.　%.　However,　the　degree　of　diffusion　for　each　composition　does　not　change　significantly.　More　importantly,　ultra-high　thermally　stable　dielectric　responses　in　a　wide　temperature　range　are　obtained　in　NN-xBMT.　Especially　in　x　=　0.03,　its　permittivity　is　around　500　at　room　temperature　and　shows　a　variation　less　than　4.4%　from　30　to　150　°C.　Our　results　may　have　some　guiding　significance　for　the　preparation　of　NN-based　ceramics　with　specific　TC,　and　are　significantly　important　for　capacitor　applications　requiring　a　wide　temperature　range　stability.　©　2019　Elsevier　Ltd　and　Techna　Group　S.r.l.