Abstract: A novel high temperature composite phase change thermal storage material was prepared by one-way compression molding using aluminum powders as the phase change material. The phase change thermal storage materials were investigated by metallographic microscopy and scanning electron microscopy. The mixability, surface morphology, microstructures, and constituent structure of phase change thermal storage materials were analyzed to study the preparation mechanism and influence factors in compacting process. At the same time, the liquidity, stacking density, and particle size ratio were also analyzed. The results show that, the constituents of solid and liquid phases are not changed during the compacting process, the macroscopic and microcosmic changes are mainly in the shape of pores and particles. With the pressure and holding time increasing, the density and intensity of materials increase, the porosity decreases, and the macroscopic distribution of materials are distributed uniformly.