As　thermal　energy　storage　and　heat　transfer　material,　molten　salt　is　widely　used　in　concentrating　solar　power　(CSP)　plant.　The　thermophysical　properties　of　molten　salt　can　be　significantly　changed　by　adding　nanoparticles　into　molten　salt.　In　this　work,　the　heat　transfer　characteristics　of　quaternary　mixed　molten　salt　with　SiO2　nanoparticles　are　experimentally　studied.　The　results　show　that　the　heat　transfer　performance　of　molten　salt　based　nanofluids　is　better　than　that　of　pure　molten　salt.　The　convection　heat　transfer　coefficient　and　Nu　number　of　molten　salt　based　nanofluids　are　22.34%　and　11.42%　higher　than　that　of　pure　molten　salt,　respectively.　The　classical　heat　transfer　correlation　equations　are　not　suitable　for　quaternary　mixed　molten　salt　based　nanofluids.　The　heat　transfer　correlation　of　quaternary　mixed　molten　salt　based　nanofluids　is　fitted,　the　maximum　deviation　between　the　experimental　data　and　fitted　heat　transfer　correlation　of　molten　salt　based　nanofluids　is　12%.　This　work　could　provide　basic　heat　transfer　data　of　molten　salt　based　nanofluids　for　thermal　energy　storage　application.