An optical microstructure plate and mold for fabricating the same is disclosed. The optical microstructure plate comprises a substrate. An optical microstructure element is formed on the substrate. A period alignment mark is disposed on the substrate to provide alignment for fabricating the optical microstructure element by a mold. A universal alignment mark is disposed on the substrate to provide alignment for bonding another plate therewith. Specifically, the mold comprises a concave within a mold substrate, a spoiler around the concave, and a buffer zone adjacent to the spoiler.