Borehole TV is a geophysical approach of obtaining directly the original image of borehole wall. With advanced time-timer, improved optical technique, high-resolution camera with human-machine interaction of color adjustment, and eliminated impact of electromagnetic fields on the image data, high-resolution digital borehole TV technology has characteristics of high precision, high resolution and high fidelity. It was applied to the research on the visualization of thick overburden layer of the dam site and the cofferdam of a hydropower station. High-resolution original images of borehole wall were obtained, and the geological conditions of the project area was detected. The technology provides technical support for the project construction, and lays foundation for digital electronic rock core database.