Abstract Thermosetting polyurethane based on Polyethylene glyol and Polyaryl polymethylene isocyanate was prepared through solvent-free bulk polymerization for solid-solid phase change materials. Chemical structure, crystallization behavior, phase change behavior, thermal reliability and thermal stability of Polyethylene glyol based phase change materials were extensively studied by fourier transform infrared spectroscopy, X-ray diffraction, polarizing optical microscopy, differential scanning calorimetry, thermal cycling testing and thermogravimetric analysis, respectively. The polarizing optical microscopy and X-ray diffraction results indicated that the crystal structure of prepared phase change materials was not affected by the crosslink structure. Differential scanning calorimetry measurements showed that prepared phase change materials possess high latent heat and appropriate phase change temperature for the application of thermal energy storage. The maximum latent heat of phase change materials in melting and freezing process reached 111.7 J/g and 110.4 J/g, respectively. Thermal cycling test and thermogravimetric analysis results demonstrated the good thermal reliability and stability of prepared phase change materials. The prepared phase change materials showed the potential for thermal energy storage application and will make an effective utilization of waste energy.