A highly reliable, self-destructing syringe with normal capacity dependent on a clamping piece position comprises a jacket (1), a core rod (2), a piston (3) and a clamping piece (4). A self-destructing feature area (22) and a self-destructing boss (21) for limiting the clamping piece (4) are arranged at the front end of the core rod (2). The length of the self-destructing feature area (22) matches the axial length of the clamping piece (4). The piston (3) matching an inner cavity of the jacket (1) is sleeved at a core-rod end of the front end of the self-destructing boss (21). A clamped structure (23) for controlling movement of the clamping piece (4) is arranged on the core rod (2) and consists of a plurality of conical steps which are coaxial with the core rod (2) and are sequentially stacked from front to back. The clamping piece (4) is movably clamped on the clamped structure (23), and the initial assembly position of the clamping piece (4) on the clamped structure (23) is dependent on the required dose of liquid medicine to be injected. The length of the clamped structure (23) is sufficient, so that when the core rod (2) assembled with the piston (3) is pushed to the sealed bottom of the inner cavity of a barrel of the jacket (1), the last conical step (232) of the clamped structure (23) extends all along to reach or get close to a tail curl edge (12) of the jacket (1), and even if the clamping piece (4) is combined with the same core rod (2), syringes with different sizes can be designed by changing the assembly position of the clamping piece (4) on the clamped structure (23) of the core rod (2). The core rod is high in universality, and the highly reliable, self-destructing syringe is low in manufacturing cost, accurate in dosage, good in backstop effect and high in reliability.Linvention concerne une seringue autodestructrice, hautement fiable, dotée dune capacité normale dépendant dune position de pièce à bride, comprenant un manchon (1), une tige centrale
