Energy transition is the key to solving environmental problems in the energy sector, and the development and utilization of clean energy and industrial energy conservation are more effective solutions. Among them, the application of the energy storage system is an important link, and the performance of the heat storage molten salt will directly affect the conversion and utilization of the entire energy heat exchange system. In this paper, a kind of NaCl-KCl-FeCl3 mixed chloride molten salt with a mass ratio of 35:10:55 was prepared by the grinding method, using synchronous thermal analyzer (STA), transient plane heat source method, microscopic morphology analysis, and corrosion dynamic curve to characterize the melting point, thermogravimetry, thermal conductivity, and corrosion properties of the material. It was found that the melting point of the ternary chloride is 140.4°C, the molten salt can work stably at high temperatures, and its thermal conductivity increases with the increase in temperature. The 316L steel sheet is mixed with NaCl-KCl-FeCl3 at 350°C among the chloride molten salts, which has better corrosion resistance. The material has the advantages of low melting point, relatively stable under high temperatures, low viscosity, and low corrosiveness to 316L steel sheets, and is expected to be used in fields such as building energy saving and industrial waste heat utilization.