A uniplanar pedicle screw comprises a screw base, a positioning compression ring and a ball-head screw. Lateral bosses are provided at left and right sides of an upper portion of a ball head of the ball-head screw, and upper side surfaces of the lateral bosses are arc-shaped and project upwards. A central boss is provided on the ball head of the ball-head screw between the two lateral bosses, and an upper side surface of the central boss is arc-shaped and protrudes upwards. An arc center of the central boss and a connecting line of arc centers of the two lateral bosses are on the same straight line. Arc-shaped concave surfaces matching the two lateral bosses are provided at a lower portion of the positioning compression ring and at left and right sides of a rod accommodating groove.
