A needle-exchangeable and self-destruction insulin syringe comprises a barrel (1), a push rod (2), a rubber piston (3) and a needle seat (4). The barrel (1) is provided with a connection needle seat (7) matched with a needle hub (5). The connection needle seat (7) is supported and fastened at the front end of the barrel by a support seat (8). The needle hub (5) is extended downwards to form a fixing ring (9). A snap ring (10) is formed at the upper end of the connection needle seat (7). The snap ring (10) is protruded into the bore of the fixing ring (9) and locked with the fixing ring (9). A large groove (13) is provided in the wall of the bore of the connection needle seat (7). The upper end of the support seat (8) is protruded into the bore of the connection needle seat (7). First elastic detents (14) are formed at the upper end of the support seat (8) and come together towards the center. A ring of flange (15) is provided at the outside of the upper end of the support seat, and falls in the large groove (13), capable of sliding up and down along the large groove (13). First elastic support pawls (16) are formed at the lower end of the connection needle seat (7), and the inner wall of the barrel is correspondingly provided with a small groove (17) in which the first elastic support pawls (16) can be embedded. A ring of flange shoulder (18) is provided at the outside of the lower end of the support seat, and abuts against the first elastic support pawls (16).
