The polyethylene glycol/cement composites as thermal energy storage materials were prepared by blending polyethylene glycol and cement. In composite materials, polyethylene glycol (PEG) is used as the phase change material for thermal energy storage and cement acts as the supporting material. A Fourier transformation infrared spectroscope (FT-IR), x-ray diffractometer (XRD), and scanning electronic microscope (SEM) were used to determine the chemical structure, the crystalloid phase, and microstructure of the polyethylene glycol/cement composites, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA). The SEM results showed that the polyethylene glycol was well dispersed in the porous network of the cement.