The present invention disclosed a retractable self-destroying safety syringe with replaceable needle including a barrel body, a needle base body (3) disposed in a barrel neck (2) at an end of the barrel body (1), an elastic buffering engaging mechanism formed between the barrel neck (2) and the needle base body (3). An asymmetrical elastic retracting locking member having an elastic function is disposed at an end of a plunger, with which an internal sleeved retracting locking member of the needle base body can be interlocked by the elastic function. After being retracted into the barrel body (1), the needle base body is deflected to one side under an asymmetric force, and the needle therefore inclines in a direction nearly a 45 degree angle to one side of the inner wall of the barrel body (1) and is blocked by the barrel neck of the barrel body, so that the needle and the needle base could not be pushed out of the barrel neck again and self-destruction of the syringe is truly achieved. The asymmetrical elastic retracting locking member is a hook (12) made of plastic material, which is formed with the plunger body by one-time molding process.
