A method for making an optical plate formed with a microstructure includes: extruding a substrate material and advancing the same to pass through a first nip formed between an embossing roller and a first pressing roller, the embossing roller having a micropatterned surface formed with a plurality of protrusions and a plurality of grooves, the protrusions and the grooves cooperatively defining a microstructure-forming space; applying a photosensitive resin to the micropatterned surface and filling the same into the microstructure-forming space upstream of the first nip to form a plurality of microelements respectively in the microstructure-forming space; allowing the photosensitive resin applied to the micropatterned surface to pass through the first nip together with the substrate material, thereby bonding the microelements to the substrate material; and irradiating and curing the photosensitive resin downstream of the first nip to form the optical plate.