Nickel-based single-crystal superalloys are extensively applied in aero-engines due to their superior high-temperature performance. However, in coastal and marine environments, they are highly susceptible to hot corrosion induced by Na₂SO₄ and NaCl deposits. Previous studies have revealed that mixed salts accelerate the degradation of protective oxide scale and intensify the internal corrosion, thus significantly reducing the service life of alloy components. Nevertheless, systematic investigations on the hot corrosion behavior of low-Re second-generation single-crystal superalloys in different salt environments remain scarce, and the underlying mechanisms require further clarification. Therefore, the hot corrosion behavior of a low-Re second-generation single-crystal superalloy at 900 ℃ beneath deposits of pure Na₂SO₄ and mixed Na₂SO₄/NaCl salts in air was investigated using the discontinuous weight change measurement method. Results show that the Na₂SO₄/NaCl mixed salt exhibits more severe corrosive effect, manifested by intensified oxide scale spallation, increased corrosion products thickness, and aggravated internal corrosion. Beneath the pure Na₂SO₄ salt deposit, a relatively continuous Al₂O₃ protective oxide scale is formed on the alloy surface, whereas beneath the mixed salt, the synergistic action of Cl^- and S^- triggers a chlorination-oxidation cycle and sulfidation reactions, which compromise the oxide scale integrity and accelerate the deterioration of the alloy.