The invention discloses a self-positioning metal nail which comprises a nail cap, a nail body, a nail point and a positioning block, wherein the nail cap is positioned at the top of one end of the nail body; the nail point is positioned at the bottom of the other end of the nail body; the nail cap and the nail body are integrally connected; the nail body and the nail point are integrally connected; the positioning block takes the shape of a circular truncated cone; a circular hole cavity is formed in the middle of the positioning block; the positioning block is mounted between the bottom of the nail body and a position above the nail point; and a smaller end of the positioning block is positioned below. According to the self-positioning metal nail, the circular truncated cone shaped positioning block is used on the nail body in a matched manner; when the self-positioning metal nail is used, the positioning block is knocked into a hammering point of the metal nail, then, the nail point is inserted in the circular hole cavity of the positioning block, the nail cap is knocked, and the metal nail is prevented from being handheld for positioning; and during the knocking process, the metal nail is unlikely to incline or bend, so that finger safety is protected, the mounting damage rate of the metal nail is reduced, and the operation is convenient.