Abstract: Site inspection on the hydraulic structures is an important means to ensure the safety of power plant operation. However, the inspection of pressure pipeline with many bends in high-head hydropower station has not been developed for a long time because of inspection means restriction. Combined with the actual situation of Ertan Hydropower Station, the underwater inspection method of pressure pipeline was developed. Under the water-filled condition of the pressure pipe, the Remotely Operated Vehicle was used to photograph underwater. The application of ROV technology in inspection of pressure pipeline with multi-bend segment in high-head Hydropower Station was realized for the first time. And the inspection result is up to the expected requirement. The ROV technology can be used as reference to the later operation and maintenance personnel of similar projects.