Abstract: The dielectric properties and relaxation of BaNb₂O₆ doped Na_1/2Bi_1/2TiO₃ lead-free piezoelectric ceramics were investigated.X-ray diffraction shows that BaNb₂O₆ diffuses into the lattice of Na_1/2Bi_1/2TiO₃ to form a solid solution with perovskite-type structure.The temperature dependence of dielectric constant ε_r reveals that the solid solution has two dielectric abnormal peaks.The thermal variation of the permittivity is well described by a law 1/ε-1/ε_m=C（T-T_m）^γ and the diffuse coefficient γ value increases with the increasing concentration of BaNb₂O₆.All samples exhibited relaxor characteristics different from classic relaxor ferroelectrics.The samples with low doping level of BaNb₂O₆ exhibits obvious frequency dependence only near the low temperature dielectric abnormal peak Tf,and the samples with a high doping level of BaNb₂O₆ exhibits obvious frequency dependence between room temperature and Tf.The mechanism of relaxor behavior was also discussed according to the macro-domain to micro-domain transition theory.