Abstract: The porous materials and organic phase-changing materials were selected to fabricate a granulated phase-changing composite for energy storage. The energy-storing performance, durability and heat insulation of this composite were studied. The results show that organic phase-changing materials can penetrate into the porous space of pore diameters from sub-micrometers to several hundreds micrometers, and occupy major part of the porous space. The resulting composite exhibits outstanding energy-storing performance and good durability. The phase-changing behavior is influenced by the volume fraction of organic phase-changing materials and the porous structure. The energy saving performance of the composite for building is superior to that of expanded perlite.