The 0.1 La(Mg0.5Ti0.5)O3(0.9-x)CaTiO3x(Li0.5Sm0.5)TiO3 (LMTCTLST,x=0.1~0.6) ceramics were prepared by the conventional solidstate reaction process. The phase composition, microstructures and microwave dielectric properties of the multiphase ceramics were investigated. The XRD results suggest that a single perovskite structure were formed for the LMTCTLST ceramics. The SEM result showed that the grain sizes of the sample were increased with the increase of (Li0.5Sm0.5)TiO3 content. At x= 0.6, the grains were appeared abnormal phenomenon, it has a great influence on the microwave dielectric properties of the samples. After adding (Li0.5Sm0.5)TiO3 content into the system, the permittivity (εr) slightly decreased from 121.56 to 117.5 when x varied from 0.1 to 0.6. Mean while, the corresponding quality factor (Q×f) observably decreased from 10 055.71 GHz to 4 042.15 GHz. In addition, the temperature coefficient of resonant frequency (τf) was gradually shifted to the negative direction with the increase of (Li0.5Sm0.5)TiO3. The LMTCTLST ceramics with x=0.6, sintered at 1 340 ℃ for 4 h, showed the excellent microwave dielectric properties of permittivity εr ≈ 117.5, quality factor Q×f≈4 042.15 GHz (f=3.415 GHz) and a almost nearzero temperature coefficient of resonant frequency τf≈10.13×10-6/℃.