As　a　medium　and　high　temperature　heat　storage　medium,　the　thermal　performance　of　molten　salt　plays　an　important　role　in　the　thermal　energy　storage　system.　In　order　to　improve　the　specific　heat　capacity　and　thermal　conductivity　of　molten　salt,　a　mechanical　dispersion　method　is　used　to　prepare　a　shape-stable　composite　phase　change　material　for　thermal　energy　storage.　Nitrate　(NaNO3)　has　a　higher　phase　change　latent　heat,　which　was　chosen　to　combined　with　different　nanoparticles　(SiO2,　SiO2+TiO2)　to　improve　its　specific　heat　capacity,　and　with　expanded　graphite　(EG)　as　a　carrier　matrix　to　improve　thermal　conductivity.　Through　the　characterization　of　its　chemical　compatibility　and　thermophysical　properties,　the　results　show　that　the　nanoparticles,　EG　and　NaNO3　have　good　chemical　compatibility.　Compared　to　NaNO3,　the　thermophysical　properties　of　composite　(NaNO3:(SiO2+TiO2):EG　=　84%:0.1%　+　0.9%:15%,　mass　ratio)　was　improved　obviously.　The　average　specific　heat　capacity　before　the　phase　change　increased　from　1.45 J/(g·K)　to　1.81 J/(g·K),　and　the　average　specific　heat　capacity　after　the　phase　change　increased　from　1.69 J/(g·K)　to　2.47 J/(g·K);　The　thermal　conductivity　is　about　13.9　times　higher　than　that　of　NaNO3;　in　the　range　of　100–380°C,　the　heat　storage　density　of　the　composites　is　about　679.2 kJ/kg　300　thermal　stability　tests　showed　that　the　latent　heat　of　the　composites　is　reduced　by　7.4%,　and　the　specific　heat　capacity　before　and　after　the　phase　change　is　reduced　by　6.1　and　6.0%,　respectively.　The　research　can　provide　a　broad　application　prospects　in　the　field　of　medium　temperature　energy　storage.　Copyright　©　2022　Song,　Lu,　Fan　and　Wu.