The chloride-based molten salt is expected to be the next generation of heat storage medium for concentrated solar power technology. However, the chloride-based molten salts have severer corrosive effect to the relevant metallic structural parts at elevated temperatures. In this paper, Ni-Al coatings were prepared on Ni-based alloy IN 625 by magnetron sputtering technique. Then the coated alloys were pre-oxidized in air at different temperatures. Next, the corrosion behavior of the pre-oxidized coatings in the mixed chloride molten salts at 800^oC was assessed via immersion test. Meanwhile, the formed oxide scales due to pre-oxidation treatment, and the variation of the pre-oxidized scales after immersion test were also characterized. The results show that a continuous and dense oxide scale can form when the pre-oxidation at 1000^oC. When the pre-oxidation at 800 and 900^oC, a complete and continuous dense oxide scale cannot form, and when the pre-oxidation at 1100^oC, although an oxide scale will form, but a large number of nodular oxides generate on the top surface of the pre-formed oxide scale due to the rapid outwards diffusion of alloying elements from the substrate during pre-oxidation, which is not conducive to the corrosion resistance of the coating. After corrosion in molten chloride salts at 800^oC for 100 h, the Ni-Al coated IN 625 alloy pre-oxidized at 1000^oC presented only little mass change, indicating that the coating has good high-temperature corrosion resistance, this may mainly be due to the formation of a complete and continuous oxide scale of α-Al₂O₃, which plays role in anti-corrosion protection for the substrate. With the progress of high temperature corrosion, the Cr content in the coating increases obviously, indicating that high temperature promotes the outward diffusion of Cr atoms from the substrate.