Properties　and　phase　structures　of　lead-free　piezoelectric　ceramics　0.92Na(0.5)Bi(0.5)TiO(3)-0.08BaTiO(3)　(NBT-BT)　modified　with　La2O3　have　been　studied.　Because　of　the　different　valence　and　ionic　radius　between　La3+　and　the　exchangeable　A-site　ions,　the　lattice　distortion　and　arrangement　in　the　modified　compounds　can　be　expected,　which　will　directly　influence　the　phase　composition　and　electrical　characteristics　of　NBT-BT.　Differing　from　familiar　frame　of　gradual　variability　going　with　adulteration,　NBT-BT　doping　0.2-1.0　at.%　La2O3　presents　an　abnormal　increase　of　dielectric　constant　and　a　dramatic　vanish　of　piezoelectricity.　Further　study　on　the　relaxor　property　and　domain　structure　implies　that　it　originates　from　a　typical　relaxor-to-antiferroelectric　crossover　phase　transition.　However,　a　larger　addition　of　La2O3　could　rejuvenate　the　ferroelectricity　and　piezoelectricity　of　NBT-BT,　correlating　well　with　the　model　of　competing　ferro-　and　antiferroelectric　interactions　and　metastable　intermediate　phase　behavior　in　the　morphotropic　phase　boundary　region　of　complex　perovskites.