(1-x)BaTiO3-xBiYO(3) [(1-x)BT-xBY] polycrystalline ceramics were prepared by solid-state reaction method. The ceramics are in tetragonal phase when x0.04, transform to pseudocubic at x0.06, showing a classic ferroelectric to relaxor transition at x=0.06, where the phase transition temperature was found to shift to higher temperature with increasing frequency. The dielectric permittivity peaks were analyzed by the modified Curie-Weiss law. Both parameters Tdiffuse and Trelaxor were found to increase with increasing BY content, demonstrating a stronger relaxor characteristic.