The invention discloses a stackable building block key. The stackable building block key comprises a cubic housing, an I-shaped sliding block and a spring, wherein the cubic housing is provided with a cavity inside; the I-shaped sliding block is arranged on the housing movably up and down in a penetration manner; the spring is sleeved to a middle part of the sliding block; a rubber cushion used for pushing and pressing the sliding block is arranged on an upper end surface of the housing; the upper end of the spring is fixed on the housing, and the lower end of the spring is fixed on the sliding block so as to form an upward pre-tightening force to the sliding block; a limiting lug boss for limiting an up-moving position of the sliding block is arranged on the inner wall of the housing; clamping buckles are symmetrically arranged on upper parts of two opposite vertical walls of the housing; and clamping grooves spliced with the clamping buckles are symmetrically arranged on lower parts of the other two opposite vertical walls of the housing. According to the stackable building block key disclosed by the invention, the required key is heightened via the building block key sleeved to the required common keyboard key, so that a height difference is formed between the required key and nonessential keys; and thus, under the condition that only limited keys need to be used such as playing games, the problem that the keys on the keyboard with the same height are pressed wrong easily is solved.