In　order　to　study　the　effects　of　SiO2　nanoparticles　content　on　the　specific　heat　capacity　and　thermal　conductivity　of　nano-SiO2/NaNO3-KNO3/EG　composite　heat　storage　materials,　a　series　of　nano-SiO2/NaNO3-KNO3/EG　composites　were　prepared　by　mechanical　dispersion　method.　NaNO3-KNO3　and　SiO2　nanoparticles　with　different　mass　fractions　(0.1%,　0.5%,　1%,　2%,　3%)　were　used　as　heat　storage　materials　and　expanded　graphite　(EG)　was　used　as　matrix　material.　Then　the　specific　heat　and　the　thermal　diffusivity　of　composite　heat　storage　materials　were　measured,　and　the　microstructural　characteristics　were　analyzed　by　scanning　electron　microscopy　(SEM).　The　results　show　that　adding　1%　of　SiO2　nanoparticles　to　the　composite　can　significantly　affect　its　average　specific　heat　capacity　and　thermal　conductivity,　with　a　measured　value　of　3.92　J/(g•K)　and　8.47　W/(m•K),　respectively,　which　are　1.37-2.17　times　and　1.7-3.2　times　higher　than　that　of　the　other　similar　composites.　This　is　owed　to　its　high　density　network　nanostructure　with　the　large　specific　surface　area　and　high　surface　energy　which　can　improve　the　specific　heat　capacity　and　thermal　conductivity.　©　All　Right　Reserved.