Pipe fitting connecting piece

The invention relates to the technical field of pipe fitting connection, and discloses a pipe fitting connecting piece which comprises a fixed pipe fitting, a sealing ring and a locking ring. According to the device, sealing of the connecting position of the pipe fitting is achieved through mutual matching of the sealing ring and the fixed pipe fitting, then the sealing ring and the fixed pipe fitting are further locked through the second protrusion on the locking ring and the first protrusion on the fixed pipe fitting, secondary locking is achieved, and due to the fact that the sealing ribs are arranged on the inner side wall and the outer side wall of the sealing ring, the sealing effect is good. The sealing ribs extend downwards in an inclined mode, so that when the shape change trend occurs at the pipeline connecting position due to overlarge pressure or overheat expansion, the sealing ribs enable sealing fastening force to be larger and larger under the pressure effect, the shape change trend can be effe