High　energy　ball　milling　is　a　simple　and　effective　method　in　preparing　nano-particles,　which　can　be　used　to　lower　the　size　of　starting　dielectric　powder　for　building　thin　casting　film,　favoring　to　enhance　the　capacitance　density　of　multilayer　ceramic　capacitors.　In　this　paper,　Bi0.5Na0.5TiO3-NaNbO3　(BNT-NN)　binary　system　has　been　selected　as　research　goal.　After　high　temperature　calcining,　the　obtained　pure　phase　BNT-NN　coarse　powder　was　further　pulverized　by　the　high　energy　milling　method.　The　results　reveal　that　high　energy　milling　method　can　realize　the　refinement　of　BNT-NN　nano-powders　in　a　short　time.　Using　these　nano-powders　as　precursor,　the　grain　size　of　the　densified　ceramics　decreases　by　about　one　third　in　comparison　with　those　derived　from　normal　coarse　powders.　Moreover,　the　temperature　stability　of　capacitance　of　fine　ceramics　is　below　±15%　in　a　wide　temperature　region　between　-60　oC　to　300　oC,　showing　potential　application　in　high-temperature　multilayer　ceramic　capacitors.　©　2018,　Science　Press.　All　right　reserved.