In　order　to　study　the　effects　of　EG　(expanded　graphite)　content　and　SiO2　nanoparticles　on　the　specific　heat　and　thermal　conductivity　of　nano-SiO2/NaNO3-KNO3/EG　composite　heat　storage　materials,　a　series　of　nano-SiO2/NaNO3-KNO3/EG　composites　are　prepared　by　the　aqueous　solution-ultrasound　oscillation　method.　The　nanoSiO(2)/NaNO3-KNO3　and　EG　with　different　mass　fractions　(5%,　10%,　15%　and　20%)　are　used　as　heat　storage　material　and　matrix　material,　respectively.　The　specific　heat　and　thermal　conductivity　of　the　composite　are　measured　by　STA　(Simultaneous　Thermal　Analysis)　and　LFA　(Laser　Flash　Apparatus),　respectively.　The　results　show　that　nano-SiO2/NaNO3-KNO3/EG　composite　exhibits　obvious　better　performance　than　pure　binary　nitrate　NaNO3-KNO3.　With　15　wt%　EG,　the　average　specific　heat　(from　250　degrees　C　to　430　degrees　C)　and　thermal　conductivity　of　the　composite　are　2.574　J/(g.K)　and　6.05　W/(m.K),　respectively,　which　are　1.69　times　and　9　times　higher　than　that　of　pure　binary　nitrate.　After　adding　1　wt%　nano-SiO2　to　NaNO3-KNO3/EG　(15　wt%)　composite,　the　average　specific　heat　and　thermal　conductivity　increase　by　44%　and　60.9%,　respectively.　From　the　above　results,　the　composite　heat　storage　materials　prepared　by　adding　EG　and　nano-SiO2　into　binary　nitrate　are　considered　as　promising　candidate　materials　for　high　heat　transfer　performance.