NaNbO3　sits　at　an　instability　between　its　ferroelectric　and　antiferroelectric　phases,　but　its　nanoscale　polarization　behavior　is　rarely　reported.　In　this　work,　we　produced　high-density　NaNbO3　nanostructured　ceramics　with　a　grain　size　of　50　nm　by　spark　plasma　sintering　of　nanocrystalline　powder,　which　was　obtained　by　mechanosynthesis.　The　nanostructured　ceramics　exhibited　a　symmetrical　ferroelectric　loop　and　increased　relative　permittivity.　We　believe　that　the　increased　internal　stress　at　the　nanoscale　stabilized　the　ferroelectric　domain　structure,　which　promoted　macroscopic　piezoelectricity,　demonstrating　its　potential　uses　in　nanoelectromechanical　systems.