An airtight RF coaxial connector with self-locking by snap-fastening comprises a plug connector and a socket connector, which is characterized in that the elastic locking element of the plug connector used for locking the socket outer conductor of the socket connector is fixed on the outer surface of the plug outer conductor of the plug connector along its radius; that the front end of the inner hole of the plug outer conductor of the plug connector is provided with a sealing groove; and that the sealing groove is provided with a sealing ring whose free inner diameter is shorter than the external diameter of the outer conductor of the socket connector. The chamfer at the front end of the socket connector makes pre-extrusion to the O-shaped sealing ring in the sealing groove. When the plug connector is further inserted into the socket, the conical surface on the locking bulge on the outer conductor of the socket connector re-extrudes the O-shaped sealing ring, and realizes a good sealing effect. In particular, the dual-extrusion has little damage to the sealing ring, and thus greatly increases the lifetime of the sealing ring.