In　this　work,　perovskite　Na0.5Bi0.5TiO3　is　applied　as　oxygen-defect　conductor　of　NO2　sensor　fabricated　with　CuO　as　the　sensing　electrode　and　Pt　as　reference　electrode.　Transition　metal　ion　Cu2+　serves　as　a　dopant　of　Na0.5Bi0.5TiO3　at　B　site　in　view　of　its　dual　functions　in　both　creating　as　many　oxygen　vacancies　as　possible　and　extending　the　length　of　the　triple　phase　boundaries　together　with　CuO　sensing　electrode.　The　phase　transformation　from　the　cubic　to　rhombohedral　phase　occurs　in　the　process　of　increasing　Cu2+　contents,　resulting　in　greater　lattice　distortion　and　thus　generating　more　oxygen　vacancies.　The　expansion　of　the　lattice　volume　and　the　overflowed　Bi2O3　promote　oxygen　hopping　in　the　[BO6](proportional　to)　chains　of　the　solid　electrolyte.　The　electrochemical　results　indicate　that　the　Na0.5Bi0.5Ti0.85Cu0.15O3-delta　sensor　exhibits　excellent　response-recovery　characteristics　with　high　sensitivity　(24.49　nA/ppm)　upon　exposed　to　500　ppm　NO2　at　500　degrees　C.　The　possible　coexistent　gases　affect　little　on　the　response　current　of　the　sensor　towards　NO2　gas.　The　long-term　stability　measurement　illustrates　that　there　is　only　a　slight　1.36　mu　A　drop　in　response　current　value　after　aging　storage　for　one　and　a　half　months.　The　performances　of　the　sensors　based　on　non-rare-earth　Cu-doped　Na0.5Bi0.5TiO3　solid　electrolytes　exhibit　the　better-off　application　prospect　with　low　cost　at　low-medium　temperature.