Latent heat storage (LHS) can theoretically provide large heat storage density and significantly reduce the storage material volume by using the material〖DK〗’s fusion heat.Phase change materials (PCMs) commonly suffer from low thermal conductivities.The problem of low thermal conductivity is a major issue that needs to be addressed for high temperature thermal energy storage systems.Since porous materials have high thermal conductivities and high surface areas，they can be used to form composites with PCMs to significantly enhance heat transfer.In this paper，the feasibility of using metal foams and expanded graphite to enhance the heat transfer capability of PCMs in high temperature thermal energy storage systems is investigated.The results show that the porous material can improve the heat transfer rate of pure sodium nitrate of 2.1 times.Porous materials severely inhibited natural convection in the liquid phase heating stage，the heat transfer rate of the mixture of sodium nitrate and porous materials is not more than half of the pure sodium nitrate.By comparing the heat transfer performance of the bottom heating and the top heating of the heat storage system，this paper further reveals the porous material impact on the natural convection.