The solid solution of dielectric ceramic Ca 1 - x La 2 x / 3 TiO 3 system for the composition range of 0.1 =< x =< 0.9 is studied. The crystal structure of the system is single perovskite. From the X-ray diffraction patterns, the superstructure reflection lines are detected for the composition x =< 0.5. With an increase in the substitution amount of La, the permittivity and the temperature coefficient of resonant frequency (TCF) decrease. A maximum Q x f value of 17600 appears at x = 0.4 since that the extrinsic origin for the dielectric loss degrades the Q x f value due to the poor grain growth for the composition x =< 0.5. (1-y)Ca 1 - x La 2 x / 3 TiO 3 -y(Li,Nd) 1 / 2 TiO 3 compounds are introduced to obtain a good temperature stability of resonant frequency. With x = 0.4, the composition y = 0.5 shows good temperature stability (τ f = +4.5ppm/ o C) with a high permittivity of 105 and a Q x f value of 7000 GHz.