The sintering temperature of the LiAlSiO4(LAS) ceramics, which exhibited the microwave dielectric properties of epsilon(r) = 4.8, Q x f = 36 000GHz, and tau(f)=8.0 ppm/degrees C, decreased below 960 degrees C when B2O3 was added. The B2O3-related liquid phase was formed and assisted the densification of the LAS ceramics at low temperatures. The average grain size of the specimen sintered at 950 degrees C increased with the addition of B2O3 but decreased when B2O3 exceeded 12.0 mol%, probably due to the presence of a large amount of liquid phase. The LAS ceramics containing 12.0 mol% of B2O3 sintered at 950 degrees C exhibited the excellent microwave dielectric properties of epsilon(r) = 5.3, Qxf = 212 000GHz and tau(f) = -7.7 ppm/degrees C.