The utility model discloses a multifunctional self-locking
type safety injector which comprises an injection tube body, the top and the bottom of the injection tube body are closed, the bottom of the injection tube body is communicated and connected with an injection needle, a self-locking
barrel is arranged above the injection tube body, a butt-joint tube body is connected between the injection tube body and the self-locking
barrel in a sleeved mode, and the butt-joint tube body is provided with a plurality of through holes. A movable
barrel is slidably connected into the self-locking barrel, the top of the movable barrel penetrates through the self-locking barrel to be connected with a pressing plate, the bottom of the movable barrel is connected with a
piston rod through a bolt, a
piston block is slidably connected into the injection
pipe body, and through holes matched with the
piston rod are formed in the bottom of an inner cavity of the self-locking barrel and the top of an inner cavity of the injection
pipe body. According to the technical scheme, through mutual cooperation of the arc-shaped reeds, the rectangular reeds, the self-locking columns, the penetrating holes, the self-locking holes and other components, effective self-locking can be conducted, and therefore the self-locking device is not prone to sliding in the using process, injection and extraction of the self-locking device are not affected, and the using efficiency and the working efficiency of the self-locking device are improved.