Wood has been developed with phase change heat storage function using balsa as a natural packaging material, and PEG was employed as a material for phase change heat storage (PCHS). Moreover, the thermal conductivity efficiency of the wood was be improved by in-situ synthesizing Fe3O4 in wood. The prepared PCHS wood was characterized by high solidification and melting enthalpies. The temperature of phase change ranged from 21.47 °C to 35.30 °C, consistent with the temperature range that makes humans comfortable in their body. The in-situ generation of Fe3O4 not only improves the PCHS wood's thermal conductivity efficiency, but also forms a 3D network structure with PCHS materials, thereby improving the dimensional stability. Comparing with original wood, PCHS wood shows good temperature regulation function, which can quickly convert light energy into internal energy and has a longer period of thermal radiation at low temperatures. The generated PCHS wood shows a promising application as indoor temperature regulating materials to promote building energy conservation.