Microwave dielectric ceramics are important for the mobile telecommunication devices, such as dielectric resonator, etc. The dielectric components must also be miniaturized to reduce the device size. For the application of the dielectric ceramics to microwave devices, a high-dielectric-constant (ɛr), a high quality factor (Qxf), and a near-zero temperature coefficient of resonant frequency (τf) are required. Tungsten-bronze type like BaO–Nd2O3–TiO2 (BNT) ceramics are widely used in microwave devices due to their high-dielectric-constants and low losses [1], [2] and [3]. The substitution of Bi for Nd (BNBT ceramics) can decrease the temperature coefficient of resonant frequency and increase the dielectric constant of BNT based ceramics [4] and [5]. In recent years, low-temperature-cofired ceramics (LTCC) have been developed to increase the volume efficiency by integrating passive components such as capacitors, resistor, and inductors. However, the densification temperatures of BNBT-based ceramics are above 1300 °C [6], which is too high for LTCC processing. The development of low-temperature-sintered BNBT-based ceramics is urgently desired to fabricate LTCC devices for microwave applications. However, no systematic study on the effects of sintering additives on the microstructure and microwave dielectric properties of BNBT ceramics has been reported