A safety injector with a retractable needle includes a needle cylinder (1) a needle seat (2) mounted in the fixing hole (11) at the head portion of the needle cylinder (1) and a core rod (3) with a snap structure. The upper portion on the external side of the needle seat (2) and the upper sidewall of the fixing hole (11) are provided with a stopper protrusion structure. The needle cylinder (1) and the needle seat (2) are located by the stopper protrusion structure. A self-destruction bar (5) for the needle seat (2) location and stop is mounted on the bottom of the needle seat (2). The head portion of the core rod (3) and the top of the self-destruction bar (5) snap together.
