Abstract: In order to guarantee the flow safety of transmission medium in deepwater and ultra-deepwater pipelines, the existed removal processes of hydrate blockages were reviewed. Formation, blockage and dissociation of hydrates in pipelines were analyzed. In addition, specific features, applicable conditions and field application status of various blockage-removal techniques were discussed. After such proceses were assessed for their safety hazards and causes thereof, proper solutions were proposed. The results show that determination of position and size of blockage, and control over pipeline temperature and pressure play an essential role in safe and efficient hydrate blockages removal process.