NBT-xBT@BT-BZN composite ceramic materials were prepared by wet solid-phase reaction method. The effects of NBT-xBT (x = 6, 7, 8, 9 mol%) on the phase structure, morphology and dielectric properties of NBT-xBT@BT-BZN composites were studied in detail. It is found that the introduction of BT into NBT leads to enhanced temperature stability in dielectric property. Samples with NBT-0.07BT shows good dielectric property, in which the temperature change rate of the dielectric constant at −55 °C–200 °C is −0.1% to −14.5%, meeting the requirements of X9R. These results indicate that the NBT-0.07BT@BT-BZN is a promising candidate for high temperature stable materials.