Molten　salts　are　subjected　to　heating-cooling　thermal　shock　cycle　in　the　operation　of　concentrating　solar　power　(CSP)　plant.　In　this　work,　the　quaternary　nitrate-nitrite　(QNN)　mixed　salt　and　Solar　salt　are　comparatively　studied　under　different　thermal　shock　conditions.　After　500　thermal　shock　test　cycles,　morphological　and　structural　analysis　of　samples　are　carried　out　by　wavelength　dispersive　x-ray　fluorescence　(WD-XRF),　Fourier-transform　infrared　(FTIR),　x-ray　diffraction　(XRD),　scanning　electron　microscope　(SEM)　and　energy　dispersive　spectrometer　(EDS).　Meanwhile,　thermos-physical　properties　of　samples　are　comparatively　analyzed.　The　results　show　the　average　melting　point　and　average　initial　crystal　temperature　of　QNN　mixed　salt　are　maximum　135　degrees　C,　82.6　degrees　C　lower　than　that　of　Solar　salt,　respectively.　The　decomposition　temperature　of　QNN　mixed　salt　is　maximum　52.1　degrees　C　higher　than　that　of　Solar　salt.　The　specific　heat　of　QNN　mixed　salt　increases　with　the　increasing　of　thermal　shock　temperature.　The　specific　heat　and　thermal　conductivity　of　QNN　mixed　salt　maximally　increase　15.46%　and　9.8%　compared　with　its　base　salt,　respectively.　Meanwhile,　the　thermal　conductivity　and　viscosity　of　QNN　mixed　salt　are　slight　higher　than　that　of　Solar　salt.　The　Solar　salt　viscosity　decreases　with　the　increasing　of　thermal　shock　temperature.　(C)　2021　Elsevier　Ltd.　All　rights　reserved.