Abstract: Electrolyte temperature was the key parameter to regulate the structure of plasma electrolyte oxidation (PEO) composites coatings, but its influence on the micro-pore characteristics and corrosion resistance of composites coatings had not been systematically studied. This paper focused on this core issue and PEO MgO-ZrO₂-Y₂O₃ composites coatings with different micro-pore structures were prepared through the precise regulation of the electrolyte temperature (5℃, 15℃, 25℃ and 35℃). The samples were characterized by scanning electron microscopy (SEM), X-ray computed tomography (X-CT), electrochemical corrosion test and scanning Kelvin probe (SKP) technique. It is found that the electrolyte temperature can finely regulate the pore structure of composite coating by significantly affecting the plasma discharge intensity and unit energy consumption. When the temperature is 25℃, the composites coating exhibits the best corrosion resistance, which is attributed to its lowest surface porosity (10.21%), overall porosity (11.60%) and minimum volume of pore structure. The densified microstructure effectively blocks the penetration path of the corrosive medium and significantly delays the corrosion process.