In　order　to　analyze　the　compatibility　between　the　molten　salt　of　the　third　generation　solar　thermal　power　generation　technology　and　the　materials　of　cryogenic　tank，this　article　takes　a　mixed　molten　salt　with　low　melting　point（142　℃）and　high　decomposition　temperature（＞700　℃）as　the　corrosion　environment，and　studies　the　corrosion　behavior　of　carbon　steel（A515Gr70）and　two　low　alloy　steels（Q345R，15CrMoR）in　the　mixed　molten　salt　at　450　℃　through　static　corrosion　experiments.　The　weight-loss　method　is　adopted　to　measure　the　corrosion　rates　of　different　metals.　The　microstructure，phase　composition　and　micro-area　composition　of　the　metal　corrosion　surface　are　analyzed　by　SEM，XRD　and　EDS.　The　results　show　that　carbon　steel　does　not　contain　corrosion　resistant　elements　Cr，Ni　and　Mo，and　the　corrosion　rate　is　the　highest.The　oxide　layer　on　the　surface　of　15CrMoR　is　mainly　composed　of　porous　Fe2O3，which　cannot　prevent　molten　salt　from　immersing　into　the　metal　matrix，resulting　in　increased　oxidation　and　poor　corrosion　resistance.The　oxide　layer　on　the　surface　of　Q345R　is　composed　of　FeCr2O4，NiO　and　TiO2　with　good　compactness，which　has　a　protective　effect　on　the　metal　matrix　and　has　the　best　corrosion　resistance.　©　2024　Science　Press.　All　rights　reserved.