A coating composition is provided, the starting materials of which comprise nano SiO2, film-forming substance, film-forming aid, accelerator, acid, and water. The composition has pH of 3-9. A passivated zinc-plated material is also provided. The zinc-plated material comprises zinc-plated substrate and passivated coat adhered to the surface of the zinc-plated substrate, wherein the passivated coat is formed by curing the coating composition. The coating composition can impart to the zinc-plated material excellent corrosion resistance, water resistance, high temperature resistance, surface conductivity, and adhesion to the zinc-plated substrate. Additionally, the coating composition contains no Cr6+, and satisfies the requirement of EU RoHS Directive.