The composite PCM was prepared by vacuum impregnation method. Natural bentonite and lauric acid (LA) were used as supporting material and PCM, respectively. The results show that the addition of flake graphite not only improves the thermal conductivity of the composite phase change material, but also prevents the phase change material from leaking out of the composite phase change. After 200 thermal⁃cold cycling treatment, the prepared form⁃stable composite PCM still shows a good performance of thermal reliability and has potential to be used in the thermal energy storage system.