Abstract: The paper has analyzed the rock deformation monitoring result of the double-line five-grade ship lock middle-isolated pier in Three Gorges Project. Through the analysis, we consider that the rock mass moves to the free face of the nearby ship lock chambers, because the middle-isolated pier has three free faces and its geological conditions are different in each part, and the rock deformation is complicated; two side surfaces monitoring points present same direction placement at the second, the third and the fourth head of the ship lock, it just shows that the surface rock displacement which is effeeted by geological conditions of head of the ship lock and excavation sequence of the two sides ship lock chambers. The rock mass deformation of middle-isolated pier convergence is very fast, and the current deformation is steady.