To meet the service requirements of ocean engineering equipment in complex conditions of temperature fluctuations and harsh corrosive environments, herein, high entropy alloy (HEA) coatings of AlCoCrFeNi and AlCoCrFeNiY_0.5Hf_0.4 were prepared on AH40 marine steel. The corrosion behavior of these coatings in 3.5% (mass fraction) NaCl solution over the temperature range of 0-60 ℃ was systematically investigated by means of potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy, in terms of the electrochemical characteristics, passivation film structure, corrosion morphology, and corrosion products of the coatings. The results indicate that at lower temperatures, the AlCoCrFeNiY_0.5Hf_0.4 coating exhibits excellent corrosion resistance, especially at 0 and 20 ℃, with high charge transfer impedance and stable passivation behavior. As the temperature increases, the corrosion resistance of the coating significantly deteriorates, as evidenced by an increase in corrosion current density, unstable passivation film, and the formation of local corrosion pits. The corrosion resistance of AlCoCrFeNiY_0.5Hf_0.4 coating at higher temperatures is significantly better than that of AlCoCrFeNi coating, which is related to the promotion effect of Y and Hf on the formation a more stable and dense passivation film on the coating surface. The increase in temperature has a profound impact on the electrochemical stability and corrosion mechanism of coatings, especially at high temperatures, which challenges the stability of passivation films and accelerates the corrosion rate. The results provide a meaningful reference for the design and optimization of new adaptive marine anti-corrosion coatings, and have important application prospects.