A color filter having a bi-layer metal grating is formed by nanoimprint lithography. Nanoimprint lithography, a low cost technology, includes two alternatives, i.e., hot-embossing nanoimprint lithography and UV-curable nanoimprint lithography. Manufacture steps includes providing a substrate with a polymer material layer disposed thereon. A plurality of lands and grooves are formed in the polymer material layer, and a first metal layer and a second metal layer are disposed on the surfaces of the lands and grooves, respectively. Finally, a color filter having a bi-layer metal grating is obtained.