Disclosed is a safety needle (10), comprising a needle base (30), a puncture needle (40) and a safety cap (50), wherein the puncture needle (40) is plugged into a front end of a puncture needle joint portion (31) of the needle base (30)； the safety cap (50) is arranged at a front end of the needle base (30)； a puncture needle sheath (51) of the safety cap (50), combined with an elastomer (52), is arranged in the needle base (30)； the puncture needle sheath (51) is sheathed outside the puncture needle (40)； a guide block (512) located at a rear end of the puncture needle sheath (51) extends into a locking guide slot (333) of an outer case portion (33) of the needle base (30)； the safety needle (10) is used to be connected to a front end of a syringe (20)； and the puncture needle sheath (51) of the safety cap (50) and an outer protecting case (53) are both sheathed outside the puncture needle (40). A rear end of the outer protecting case (53) abuts on a front end of the outer case portion (33) of the needle base (30) to limit the position, such that the puncture needle (40) cannot be punctured out, and the injection can only proceed after the outer protecting case (53) is firstly broken and removed so that the puncture needle sheath (51) is withdrawn into the needle base (30). After injection, the puncture needle sheath (51) can be ejected out and sheathed outside the puncture needle (40), and the guide block (512) of the puncture needle sheath (51) moves into a locking recess (337) along the locking guide slot (333) and then is locked, such that it cannot be reused. As such, it can be determined whether the safety needle (10) has been used or not.L'invention concerne une aiguille de sécurité (10), comprenant une base d'aiguille (30), une aiguille de ponction (40) et un capuchon de sécurité (50), l'aiguille de ponction (40) étant branchée dans une extrémité avant d'une partie d'articulation d'aiguille de ponction (31) de la base d'aiguille (30) ； le capuchon de sécuri
