Molten　salt　as　heat　transfer　and　storage　media　is　widely　studied.　In　order　to　meet　the　high-temperature　need　such　as　ultra-supercritical　steam　power　cycle,　low-cost　sodium　nitrate/carbonate　mixed　molten　salt　are　developed　and　prepared,　thermophysical　characteristics　of　three　different　samples　are　investigated　in　this　work.　The　minimum　values　of　melting　point　and　initial　crystal　temperature　of　sodium　nitrate/carbonate　mixed　molten　salt　are　300.7　degrees　C　(No.　3　sample)　and　281.7　degrees　C　(No.　2　sample).　The　decomposition　temperature　increases　with　the　increasing　mass　ratio　of　sodium　carbonate　in　mixed　molten　salt.　The　maximum　decomposition　temperature　of　sodium　nitrate/carbonate　mixed　salt　is　639　degrees　C　(No.　3　sample).　The　highest　average　values　of　specific　heat　and　thermal　conductivity　of　No.　1　sample　are　1.56　J/(g　K)　and　0.79　W/(m　K),　respectively.　The　viscosity　of　tested　mixed　molten　salt　increases　with　the　increasing　of　mass　ratio　of　sodium　carbonate.　The　specific　heat,　thermal　conductivity　and　viscosity　equations　of　sodium　nitrate/carbonate　mixed　salts　are　fitted.　Meanwhile,　the　sensible　thermal　energy　storage　cost　of　No.　1　sample　is　51.22%　less　than　that　of　Solar　salt.　The　No.1　molten　salt　has　excellent　thermal　shock　resistance　performance,　which　has　good　application　value　in　large-scale　high　temper-ature　thermal　energy　storage　system.