Abstract: The medium- and low-temperature phase change thermal storage systems can effectively store solar energy, low-grade industrial waste heat, and other thermal energy. They help alleviate the mismatch between energy supply and demand, promoting the integration of renewable energy and the comprehensive development of distributed energy systems. However, phase change packed bed thermal storage systems face the issue of low energy utilization efficiency when utilizing medium- and low-temperature heat sources, which has become a critical bottleneck limiting the improvement of their overall performance. This paper begins by introducing the structural composition, working principles, and internal heat transfer mechanisms of phase change packed bed thermal storage systems. It analyzes the heat transfer characteristics during the charging and discharging processes. Next, the performance evaluation methods and key influencing factors are discussed in detail, including operational parameters, material parameters, and structural parameters. The impact of these parameters on the thermal performance of packed bed thermal storage systems is further examined. Special attention is given to the effects of tank structure and size, filler structure and size, distributor design, and filling methods on the flow and heat transfer characteristics within the packed bed. Strategies for enhancing system performance through multi-parameter optimization are summarized, providing theoretical and experimental support for the optimized design and efficient operation of the packed bed thermal storage systems. Finally, the applications of phase change packed bed thermal storage systems in medium- and low-temperature fields, such as solar thermal utilization, industrial waste heat recovery, and power load leveling, are outlined. The future development prospects and challenges of this technology are also discussed.