The influence of H3BO3 or SiO2 additive (0.02% 2.00%) on the sintering temperatures, crystal structures and microwave dielectric properties of 0.61CaTiO3-0.39LaAlO3 ceramics were investigated. The results showed that the sintering temperature of 0.61CaTiO3 0.39LaAlO3 ceramics could be lowered from 1 380 ℃ to 1 340 ℃ by doping low level addition of H3BO3 or SiO2 and no phase change was observed when the addition was less than 2.00%. The microstructure of the specimen with 2.00% addition of H3BO3 was changed greatly and the density decreased rapidly because many pores were appeared. The dielectric constant (εr) and the temperature coefficient of resonant frequency (τf) of 0.61CaTiO3-0.39LaAlO3 ceramics were not significantly affected by doping H3BO3 or SiO2, but the quality factors (Q×f) dropped. The excellent microwave dielectric properties were obtained for 0.61CaTiO3-0.39LaAlO3 ceramics with 0.02% addition of H3BO3 or SiO2. The features of the ceramic specimen with H3BO3 addition are that εr is equal to 41.65, Q×f is equal to 48 565 GHz, and τf is equal to -1 μ℃-1 and εr =41.48,Q×f≈39 491 GHz, and τf =-1 μ℃-1 for SiO2 doped ceramic sample.