The multi?鄄component mixed nitrate molten salt was composed of potassium nitrate and sodium nitrate as a binary element and an additive by a static method.The properties such as melting point，heat of fusion，density，thermal conductivity and thermal stability of the molten salt were characterized by DTA thermal analysis，gravimetric method，Archimedes method and laser flashing method，etc.At the same time，the corrosion resistance of 8 metal materials in molten salt was studied.The experimental results showed that adding additives could lower the melting point，increase the heat of fusion and improve the thermal stability.When 4% additive-X was added，the thermal stability and thermal properties of the mixed molten salt were optimal，and the molten salt was less corrosive to the metal material， which would be an ideal heat transfer and heat storage medium in the future solar thermal power generation field.