Abstract: A paraffin/expanded graphite phase change material for thermal storage was prepared by impregnating a compressed expanded graphite block with paraffin. The thermal properties of the phase change materials were characterized by DSC．Results show that the latent heat of the phase change materials increases with paraffin fraction and the phase change temperature remains constant. The thermal diffusivity of the paraffin/expanded graphite phase change materials decreases with paraffin fraction. Paraffin can be uniformly absorbed in the worm-like pores of the expanded graphite by capillary forces, which can prevent paraffin from permeating outwards.