A method for manufacturing a flexible optical plate includes steps of: (A) positioning a metallic mask on a surface of a mother substrate; (B) irradiating a carbon dioxide laser beam through the metallic mask to form cavities on the surface of the mother substrate; (C) coating a polymer material on the surface of the mother substrate to fill the cavities; and (D) drying the coated polymer material to form the flexible optical plate, the flexible optical plate having a substrate on the surface of the mother substrate and microstructures protruding from the substrate and each corresponding to one of the cavities.