A self-destructive syringe, comprising: a cylinder, a needle being adhered on the cylinder or a needle holder with a needle being sleeved on the cylinder, the exterior wall of the cylinder being marked with graduation lines in black color or dark colors; a core rod being located in the cylinder; characterized in that: a non-return element being mounted in a central slot of the core rod and being located within the cylinder; a sealing plug being mounted on the core rod, the sealing plug being located on the front end of the core rod and being located within the cylinder; wherein 1) a first reciprocating area, a first ratchet groove, a second ratchet groove, a second reciprocating area, a third ratchet groove, a fourth ratchet groove and a rectangular mounting hole are sequentially arranged and located in and along the central slot of the core rod from the front end to the tail end thereof, the first reciprocating area being the area form the front end to the first ratchet groove, the second reciprocating area being the area from the second ratchet groove to the third ratchet groove; 2) the mounting hole is located between the fourth ratchet groove and the tail end of the core rod; 3) the length of the first reciprocating area is 0.5 - 2 mm longer than that of the non-return element; 4) a non-return pike and a ratchet are located on the non-return element, the non-return element is made of elastic steel sheet, the non-return element is mounted in the slot of the core rod through the mounting hole and is initially mounted between the third ratchet groove and the fourth ratchet groove. a cylinder, a needle being adhered on the cylinder or a needle holder with a needle being sleeved on the cylinder, the exterior wall of the cylinder being marked with graduation lines in black color or dark colors; a core rod being located in the cylinder; characterized in that: a non-return element being mounted in a central slot of the core rod and being located within the cylinder; a sealing plug being mounted on the core rod, the sealing plug being located on the front end of the core rod and being located within the cylinder; wherein 1) a first reciprocating area, a first ratchet groove, a second ratchet groove, a second reciprocating area, a third ratchet groove, a fourth ratchet groove and a rectangular mounting hole are sequentially arranged and located in and along the central slot of the core rod from the front end to the tail end thereof, the first reciprocating area being the area form the front end to the first ratchet groove, the second reciprocating area being the area from the second ratchet groove to the third ratchet groove; 2) the mounting hole is located between the fourth ratchet groove and the tail end of the core rod; 3) the length of the first reciprocating area is 0.5 - 2 mm longer than that of the non-return element; 4) a non-return pike and a ratchet are located on the non-return element, the non-return element is made of elastic steel sheet, the non-return element is mounted in the slot of the core rod through the mounting hole and is initially mounted between the third ratchet groove and the fourth ratchet groove. 1) a first reciprocating area, a first ratchet groove, a second ratchet groove, a second reciprocating area, a third ratchet groove, a fourth ratchet groove and a rectangular mounting hole are sequentially arranged and located in and along the central slot of the core rod from the front end to the tail end thereof, the first reciprocating area being the area form the front end to the first ratchet groove, the second reciprocating area being the area from the second ratchet groove to the third ratchet groove; 2) the mounting hole is located between the fourth ratchet groove and the tail end of the core rod; 3) the length of the first reciprocating area is 0.5 - 2 mm longer than that of the non-return element; 4) a non-return pike and a ratchet are located on the non-return element, the non-return element is made of elastic steel sheet, the non-return element is mounted in the slot of the core rod through the mounting hole and is initially mounted between the third ratchet groove and the fourth ratchet groove.