A disposable safety self-destroyed syringe comprises a plunger and a syringe tube. An end of the plunger is sleeved with a piston, and an elastic protrusive column is coupled inside the piston with its front end being protruded to a distance from a top surface of the piston the plunger is inserted into the syringe tube from its front end for injection, and the rear end of the syringe tube is contracted radially to form a needle seat having a blocking portion on the inner wall to be conjoined with a needle, so that when the plunger is depressed to reach closely to the rear end of the syringe tube, a front end of the protrusive column is inserted into the needle seat and is stopped by the blocking portion on the inner wall of the needle seat to retain the protrusive column inside the needle seat.
