The employment of solar energy in recent years has reached a remarkable edge. It has become even more popular as the cost of fossil fuel continues to rise. Energy storage system improves an adjustability and marketability of solar thermal and allowing it to produce electricity in demand. This study attempted to prepare cordierite/mullite composite ceramics used as solar thermal storage material from calcined bauxite, talcum, soda feldspar, potassium feldspar, quartz, and mullite. The thermal physical performances were evaluated and characterized by XRD, SEM, EPMA, and EDS. It was found that the optimum sintering temperature was 1280 degrees C for preparing, and the corresponding water adsorption was 11.25%, apparent porosity was 23.59%, bulk density was 2.10mg cm(-3), bending strength was 88.52MPa. The residual bending strength of specimen sintered at 1280 degrees C after thermal shock of 30 times decreased to be 57MPa that was 36% lower than that before. The thermal conductivity of samples sintered at 1280 degrees C was tested to be 2.20W center dot (m center dotK) (-1) (26 degrees C), and after wrapped a PCM (phase change materials) of K2SO4, the thermal storage density was 933kJ center dot kg(-1) with the temperature difference (T) ranged in 0-800 degrees C. The prepared cordierite/mullite composite ceramic was proved to be a promising material for solar thermal energy storage.