A key plate includes a light-permeable covering plate having a plurality of first key openings and includes a key symbol display plate disposed on the light-permeable covering plate and having a plurality of second key openings and a plurality of light-permeable key symbol blocks. The light-permeable key symbol blocks are positioned proximate to the second key openings, respectively. The second key openings correspond in position to the first key openings, respectively. Further provided is an illuminated keyboard with the key plate. Accordingly, the key plate and the illuminated keyboard feature simplified structure, low manufacturing costs, and short manufacturing process, prevent users' fingers from hiding symbols displayed on the keys in bright and dark environments, prevent the symbols displayed on the keys from getting blurred or smeared after long contact with the users' fingers, and feature variable appearance of the key symbol display plate.