Heat　storage　is　a　key　technology　in　solar　thermal　power,　helps　solar　thermal　power　eliminate　the　instability　in　energy　supply　for　the　grid,　and　provides　continuous　and　stable　high-quality　electrical　energy　to　improve　power　system　efficiency　and　extend　system　life.　Molten　salt　is　an　important　material　for　heat　storage　and　heat　transfer　in　solar　thermal　power.　In　recent　years,　nanofluid　technology　has　been　applied　to　investigate　heat　storage　and　transfer　materials,　such　as　molten　salt,　to　improve　heat　capacity.　However,　the　nanofluid　technology　is　hampered　by　the　easy　agglomeration　of　nanoparticles　in　molten　salts,　and　this　phenomenon　degrades　the　performance　of　the　molten　salt　nanofluids.　To　reduce　or　prevent　agglomeration,　a　two-step　method　with　high-temperature　melting　in　preparing　molten　salt　nanofluids　is　developed　recently.　Molten　salt　nanofluids　obtained　by　high-temperature　melting　show　good　stability　and　long　time　to　agglomerate.　This　paper　presented　the　study　on　the　thermophysical　properties　of　molten　salt　nanofluids　prepared　by　high-temperature　melting　method.　The　molten　salt　nanofluids　possessed　low-melting　point　salt　as　base　liquid　and　SiO2　with　a　diameter　of　20　nm　as　nanoparticles.　The　specific　heat　of　this　type　of　molten　salt　nanofluid　was　tested,　and　the　optimum　concentration　of　nanoparticles　was　determined.　Results　showed　that　the　specific　heat　capacities　of　the　molten　salt　nanofluid　samples　with　different　mass　fractions　of　nanoparticles　were　higher　than　those　of　pure　molten　salt.　The　average　specific　heat　of　molten　salt　nanofluid　with　a　mass　fraction　of　0.5%　was　the　highest　at　1.950　J/(g　K),　which　was　24.5%　more　than　that　of　pure　molten　salt.　The　thermophysical　properties　of　molten　salt　nanofluids　with　a　mass　fraction　of　0.5%　and　prepared　by　high-temperature　melting　were　experimentally　tested　and　compared　with　those　of　pure　molten　salt.　These　properties　included　melting　point,　primary　crystallization　point,　thermal　conductivity,　viscosity,　latent　heat,　and　density.　The　molten　salt　nanofluids　showed　good　performance　for　heat　storage　and　transfer.