The　sol-gel　method　in　combination　with　spark　plasma　sintering　(SPS)　has　been　applied　to　prepare　NaNbO3　fine-grained　ceramics.　The　results　reveal　that　perovskite　type　NaNbO3　nano-powders　with　mean　size　of　40　nm　can　be　synthesized　by　an　aqueous　sol-gel　route.　Subsequently,　using　the　resulted　NaNbO3　nano-powders　as　precursors,　dense　ceramics　with　mean　grain　size　of　1~2　μm　are　obtained　by　SPS　method.　The　electrical　measurement　confirms　that　the　defect　dipoles　play　the　roles　in　assisting　antiferroelectric　to　ferroelectric　(AFE-FE)　phase　transition.　Moreover,　the　dielectric　constant　exhibits　good　frequency　stability　and　the　loss　tangent　is　as　low　as　0.018　(1　kHz).　©　2018,　Science　Press.　All　right　reserved.