Li7La3Zr2O12 (LLZO) powder was mixed with and thus introduced into Li0.35La0.55TiO3 (LLTO) ceramics. After high-temperature sintering LLZO phase disappeared. The cooperative introduction of Li, La and Zr elements into LLTO might modify the grain boundary region and thus change the electrical properties of the grain boundary, leading to the conductivity enhancement. The LLTO ceramics sintered at 1350°C with 10wt% LLZO powder introduced in the starting materials exhibit a high total conductivity of near 10−4 S/cm and a grain boundary conductivity of 1.1×10−4 S/cm at room temperature.