The axial length of the 1-6# dam section of the Three Gorges left bank plant is 229.8m, and a high slope of nearly 70m was formed after the foundation excavation. Due to the combination of fractures, the sliding surface is unfavorable and tends to be downstream. Reinforcement treatment mainly adopts 3000KN grade prestressing anchor cable, total 218 bundles, length 30-55m, drilling hole diameter 165, total footage 8445.6m. Anchor cable construction and steel pipe trench excavation are carried out cross. After construction monitoring, the actual elongation of the anchor cable matches well with the theoretical value, and the loss of locking anchorage is 1%~3%, which meets the design requirements.