Sodium　niobate　(NaNbO3)　is　an　important　lead-free　electronic　ceramic,　but　it　is　difficult　to　obtain　high　sintering　densification　due　to　the　strong　volatility　of　alkali　metal　elements.　Reducing　particle　size　of　the　precursor　powder　is　believed　to　be　an　effective　method　to　improve　sintering　activity,　further　to　achieve　high　densification.　In　this　work,　pure　perovskite　NaNbO3　nanoparticles　with　mean　size　of　15　nm　have　been　synthesized　by　a　facile　one-step　route　using　the　mechanochemical　method.　The　evolution　of　crystal　structure　and　morphology　of　the　particles　milled　for　different　times　were　investigated,　and　a　transformation　mechanism　has　been　proposed　to　elucidate　the　formation　processes　of　NaNbO3　nanoparticles.　Furthermore,　high-density　(98%)　NaNbO3　ceramics　were　successfully　prepared　from　nanoparticle　compact　without　any　sintering　additives.　In　addition　to　the　Curie　temperature　of　360　degrees　C,　a　diffuse　dielectric　peak　similar　to　100　degrees　C　has　been　observed,　evidencing　an　intrinsic　P-Q　phase　transition.　After　the　polarizing　treatment,　the　obtained　NaNbO3　ceramic　exhibited　a　high　piezoelectric　coefficient,　d(33)　=　37　pC/N.　(C)　2016　Elsevier　B.V.　All　rights　reserved.