The invention belongs to the technical field of pipeline sealing and blocking, and particularly relates to a pipeline sealing and blocking device. The pipeline sealing and blocking device comprises asealing and blocking leather bowl, a vertical support, a hydraulic driving mechanism and a horizontal support, wherein the sealing and blocking leather bowl is matched with the inner diameter of a pipeline; the vertical support is used for extending into a pipeline wellhead to place the sealing and blocking leather bowl into the pipeline; the hydraulic driving mechanism is connected with the sealing and blocking leather bowl and used for driving the sealing and blocking leather bowl to push the inner wall of the pipeline so as to seal and block the pipeline; and the horizontal support is usedfor being arranged outside the pipeline wellhead so as to fix the vertical support. According to the pipeline sealing and blocking device, the vertical support extends into the pipeline well so as toseal and block the pipeline, reverse operation is carried out during disassembling, the safety risk of a diver entering the pipeline well is reduced, the construction period is shortened, and the costis reduced.