The invention discloses a small-caliber projectile with a deformable flexible empennage and an implementation method thereof. According to the small-caliber projectile, a brush-type empennage is installed on the tail portion of a projectile body of the small-caliber projectile, and materials with light weight and good flexibility are adopted; in the storage and transportation process, hairs are restrained by a launcher and curled in an installation hole and abutted against the inner wall of the launcher, if vibration occurs, friction is generated between the hairs and the inner wall of the launcher, and the relative position between the projectile body and the launcher is stabilized to improve stability of the projectile body in the transportation process; when the projectile is fired andlaunched, the projectile body is launched from the launcher, the hairs are released from the restraint of the launcher, and transient high temperature occurs in the process in which the projectile body leaves the launcher, so that hardness of the hairs is enhanced, each cluster of the hairs is uprightly unfolded from the installation hole to form a fixed brush-type empennage in the air, and the projectile body can stably fly; stable installation and fixing of a fuse are achieved through a circular electrode to prevent interference of complex electromagnetic signals and improve sealing performance in the launcher.