A latching type self-destroying syringe includes a hollow barrel (1), a plunger-rod (2) sliding in the barrel (1), and a piston (3) which is installed on the front end of the plunger-rod (2). There is a needle holder (4) installed on the front end of the barrel (1), a round board (14) provided on the plunger-rod (2), and elastic pawls (15) provided on the round board (14), beveled angularly extending to the wall of the barrel (1). A diameter-increasing part (6) is provided at the tail end of the barrel (1), and an inclined step (8) is provided at the transition between the diameter non-increasing part (7) and the diameter-increasing part (6) of the barrel (1). The inclined step (8) is provided with a groove (9) at its underside, and the elastic pawls (15) can be locked in the groove (9), when pulling the plunger-rod (2) downward. A retainer ring (10) which can retain the bottom of the round board (14) is provided in the diameter-increasing part (6).
