A safety self-disposable syringe with a replaceable needle comprises a barrel body (22), an inner needle seat body (3), and a core pin (4). The needle seat body (3) is disposed in a barrel neck (2) at an end portion of the barrel body (22). A replaceable needle seat (6) is disposed at an end portion of the inner needle seat body (3). A needle tube (7) is provided on an upper end portion of the replaceable needle seat (6). An upper portion of the inner needle seat body (3) forms a replaceable needle assembling portion (9). A lower portion of the inner needle seat body (3) forms an elastic sealing stop portion (10). The replaceable needle assembling portion (9) and the elastic sealing stop portion (10) are formed into an integral single structure. A retraction locking member (20) is disposed on an end portion of the core pin (4). The replaceable needle seat (6) and the inner needle seat body (3) are fitted in a rotary manner. An elastic buffer area of the inner needle seat body (3) can guarantee the clamping force and sealing between the inner needle seat body (3) and the barrel neck (2), and reduce the force for pulling back the inner needle seat body (3) during retraction of the inner needle seat body (3), achieving a desirable balance between the two contradictory key factors. The inner needle seat body (3) can be formed through one-time injection molding. The syringe has a stable working state and good practicability.Linvention concerne une seringue de sécurité auto-jetable dotée dune aiguille remplaçable comprenant un corps (22) de cylindre, un corps (3) dappui daiguille interne, et une goupille centrale (4). Le corps (3) dappui daiguille est disposé dans un col (2) de cylindre à une partie dextrémité du corps (22) de cylindre. Un support remplaçable (6) daiguille est disposé à une partie dextrémité du corps (3) dappui daiguille interne. Un tube (7) daiguille se trouve à une partie dextrémité supérieure du support remplaçable (6) daiguille. Une partie supérieure
