This disclosure provides a sol-gel hybrid coating composition, comprising a sol-gel precursor, a polymer and a solvent, wherein the sol-gel precursor comprises tetraethyl orthosilicate and the polymer comprises polyurethane and polyacrylic. This disclosure also provides a coating process, comprising: subjecting a light metal to micro-arc oxidation treatment to form a first protection layer on the light metal, and coating the sol-gel hybrid coating composition onto the first protection layer to form a second protection layer. This disclosure further provides composite coating layers, comprising: a first layer obtained by micro-arc oxidation treatment, and a second layer obtained by dip coating with the sol-gel hybrid coating composition.