With the continuous upgrading of solar energy application technology, phase change heat storage technology has become its key technology, which is the future direction of solar water heating system in application promotion.In this paper, the types and developing trends of phase change materials, the microencapsulation of phase change material and the properties of micro-encapsulated phase change material slurries were presented.The application of phase change materials in solar water heating system was reviewed.From the energy supply and demand characteristics of solar water heating system, the improvement in the thermodymamic characteristics of phase change materials was suggested to, develop new solar water heating system, improve the utilization rate of solar energy, and reduce the conventional fossil fuel consumption and carbon emissions in the world.