The underwater maintenance robot is a special cable-type robot developed and manufactured by Yangtze River Electric Power Maintenance Works for underwater maintenance of hydropower stations with access to reservoir area, tailrace, channel, culvert and other underwater environments. The main body of the robot is 1.3 meters long, 0.9 meters wide, 0.69 meters high and 300 meters deep. The main unit carries underwater camera, navigation sonar, scanner sonar, ultra-short baseline positioning and other multi-functional carriers, which can realize underwater positioning, visual inspection, sound wave inspection, etc. Among them, sonar positioning accuracy is up to centimeter. The whole system adopts the original way of multiple layers combination, and sets up the manipulator layer, cleaning and grinding layer, sub-machine layer and crawler layer respectively. According to the actual needs, the main unit can be combined with the single or two layers of the layers respectively, which is convenient to disassemble and assemble. The robot breaks through the current single-function underwater vehicle market and integrates many functions such as camera, sonar scanning, salvage, obstacle removal, cleaning, polishing, shearing and pipeline inspection. The diameter of the cutting cable can reach 50mm, the salvage weight of the manipulator can reach more than 50kg, and the sub-function can navigate and inspect pipelines with inner diameter not less than 250mm, and the practical underwater repair work can be achieved. It can replace divers to a certain extent, ensure personal safety and improve work efficiency.