Abstract: Ship lock was one of the main engineering projects of the Three Gorges Project.The height of the high excavated slopes in the district of ship locks was generally from 70 m to 120 m,and the tallest one was about 160 m.The ground seepage was one of the important factors to affect the stability of high excavated slopes.The arrangement and construction for monitoring of ground seepage in the high excavated slopes during their construction were introduced.Based on the monitoring results during nearly three years,the development and the influence factors(such as the surface raining,drainage,fluid quality discharge and pressure of seepage in drainage hole during the construction of ship lock) were also analyzed.It was shown by monitoring data that the underground water level in north and south sides of ship lock was lower than the design water level which was basically accordant with the result calculated by Yangtze River Scientific Research Institute,and the underground water level would be immediately lowered along with the construction of project.Therefore the design seepage control method was basically reasonable.