The invention discloses a self-locking type flange pair and a flexible connecting pipe. The self-locking type flange pair comprises a locking flange, a sealing flange and a fastening ring, wherein thelocking flange and the sealing flange are connected through a bolt, and a first annular groove formed in the outer side of the top surface of the locking flange is matched with a second annular groove formed in the outer side of the surface, close to the locking flange, of the sealing flange to form an annular cavity for containing the fastening ring; aramid fiber layers are arranged on the surfaces, close to each other, of the locking flange and the sealing flange respectively; and when the self-locking type flange pair is used for connecting the end of the flexible connecting pipe, the endof a framework layer of the flexible connecting pipe is turned outwards along the top surface of the locking flange and wound around the fastening ring by a circle, then the framework layer is lockedthrough the locking flange and the sealing flange corresponding to the framework layer, and the framework layer is pressed between the two aramid fiber layers. The self-locking type flange pair is simple in structure and small in size, the self-locking type flange pair is composed of the sealing flange, the fastening piece and the locking flange in a special combination mode, rigid sections can bereduced, the flexible length can be increased, and the self-locking type flange pair has excellent pull-out resistance and vibration reduction performance.