Flexible back pressure type core holder

The utility model provides a flexible back pressure type core holder. In the holder, a right core plug is inserted into an outlet of a body module, a stepped mounting hole is formed in the axial direction, a framework unit is mounted at one end of the stepped mounting hole, and a gear ring is mounted at the other end of the stepped mounting hole; one end of the adjusting bracket is clamped at the outlet of the body module; the adjusting screw rod is rotationally mounted on the adjusting bracket and tightly presses the gear ring; a flexible pipe is sleeved in the cylindrical structure of the rigid framework, and two ends of the flexible pipe are hermetically connected with the left inner seal head and the right inner seal head respectively; a first gap is formed between the outer side wall of the rigid framework and the stepped mounting hole, and a second gap is formed between the inner side wall of the rigid framework and the flexible pipe; the first gap is communicated with the second gap through a fluid thr