The utility model discloses a pipeline isolator which is applied to the inside of a pipeline. The pipeline isolator comprises a first elastic expansion plug and a first squeeze block. The outer wall of the first elastic expansion plug and the inner wall of the pipeline are matched with each other, a groove is arranged in one side of the first elastic expansion plug, and the first squeeze block is arranged at the position of the groove. The groove and the first squeeze are both in a circular platform shape. The first squeeze block is used for squeezing the inner wall of the groove. In working, the outer wall of the first squeeze block and the inner wall of the groove are squeezed and attached, and the outer diameter of the attaching portion of the first squeeze block is larger than the inner diameter of the attaching portion of the groove. According to the pipeline isolator, the first elastic expansion plug before being expanded is pushed inside the pipeline easily, the first squeeze block is squeeze inside the groove of the first elastic expansion plug through external force, squeezing to the inner wall of the groove is formed, the first elastic expansion plug is squeezed to expand until the outer wall of the first elastic expansion plug and the inner wall of the pipeline are attached tightly, and therefore effective plugging to the pipeline is achieved. The pipeline isolator is fast in mounting, capable of bearing large pressure, and tight and long-lasting in plugging.