Lithium-based ceramics have been recognized as promising tritium breeding-materials for D-T fusion reactor blankets. Lithium silicates, Li4SiO4 and Li2SiO3, are recommended by many ITER research teams as the first selection for the solid tritium breeder. The solid-state reaction method is the most important way to synthesize lithium silicates. In present study, the processes of solid-sate reaction between amorphous silica and Li2CO3 powders was investigaed by TGA/DSC; the lithium silicate powders were synthesized at 700~900°C with different Li:Si molar ratio using solid-state reaction method. The optimized synthesis temperature and the solid-state reaction mechanism were derived on the base of experimental results.