The present invention discloses a frame for use in flat keys. The frame includes a frame body and blocking plates. The frame body holds and supports a keycap, wherein the keycap can be pressed toward the bottom of the frame body. The blocking plates are installed on the frame body and contacted the bottom surface of the keycap, wherein the blocking plates push the keycap toward the top of the frame body to maintain a predetermined distance. The frame of the present invention may be made, in one piece, from plastic such that a slim keyboard equipped with the frames of the present invention has advantages, such as low cost, swift assembly, and high quality of assembly.