A posterior cervical unilateral-open-door lateral-mass spinous process steel plate, the steel plate being stretched Z-shaped, comprises a first fixed part (1), a second fixed part (2), and a connection part (3) connecting the first fixed part (1) and the second fixed part (2). An obtuse angle is formed between the first fixed part (1) and the connection part (3), and an obtuse angle is also formed between the second fixed part (2) and the connection part (3). The steel plate is characterized in that the first fixed part (1) comprises a body part (11) arranged on an outer wall of a vertebral plate, and a spinous process fixing part (4) matched with the outer wall of a spinous process (100) the spinous process fixing part (4) is formed by upwardly bending the end of the body part (11) and has a first through hole (41) for a spinous process screw (81) to penetrate. The thickness of the spinous process is much larger than that of the vertebral plate, so from the perspective of biomechanics, the fixing effect of the spinous process screw (81) is better than the stability achieved by vertical arrangement of a screw on a vertebral plate in addition, the top of the spinous process screw (81) can be directly seen during a surgery, thereby guaranteeing that the screw (81) does not touch a vertebral canal or damage cervical cord, and enhancing the surgical safety.La présente invention concerne une plaque en acier disposée sur les apophyses épineuses et les masses latérales dans le cadre dune laminoplastie « open-door » cervicale postérieure unilatérale, ladite plaque métallique étant constituée dune plaque allongée en forme de Z et comprenant une première partie fixe (1), une seconde partie fixe (2) et une partie de raccordement (3) reliant la première partie fixe (1) et la seconde partie fixe (2). Un angle obtus est formé entre la première partie fixe (1) et la partie de raccordement (3), de même quun angle obtus est formé entre la seconde partie fixe (2) et la partie de racc
