Aiming at the submergence of the foundation pit of the power plant，the underwater blocking research is carried out. The Minjiang Qianwei navigation-power junction adopts the blocking scheme of“underwater operation + temporary blocking body + back support + flat pressure device”，which overcomes many problems such as limited working space，short construction period，high difficulty，and prominent safety hazards. It takes 9 days to successfully block the traffic corridor to ensure the progress and safety of the project. This result has filled the research gaps in this field，laid the foundation for research，and formed an invention patent at the same time.