Abstract: High-pressure isolation technique of pipeline is a new pipeline isolation technique. It is widely applied in pipe repair, pipe replacement, valve replacement, additional installing/removing manifold of onshore and offshore pipelines. It works by jointing the pig and isolation plug together. The combination is put in the pig launcher, pushed forward by the pig, the isolation plug is controlled by the ultra-low frequency signal sent from the monitoring center. The sliding lock block and the isolation ring are the key components, which are crucial for the locking and sealing capability. The paper emphasizes more on the locking stability of sliding lock block and the sealing applicability of the sealing ring. The isolation plug prototype adaptable for 300 mm pipe is developed and the plugging and boosting test are performed, which reveals its sound applicability.