Mixed molten salts are considered as promising media for both heat transfer and thermal energy storage and they have obvious advantages in solar thermal power generation, waste heat utilization and industrial process heat use. However, molten salts phase change materials still have disadvantages of low thermal conductivity. Recent studies of solid-liquid phase change energy storage processes and the state-of-the-art development of the nanocomposite phase change material were reviewed. According to the review of the future development and important research direction of solid-liquid phase change energy storage processes of nanocomposite phase change materials, it is necessary to conduct the research in various aspects including the establishment of two temperature model of phase change heat transfer in the nanocomposite melting, NC-PCM mixing process, aggregation of metal particles and thermal cycling test of NC-PCM storage unit problem.