Feitsui Dam has a height of 122.5 meters.The dam structure is directiondouble curve concrete arch, consisting of 29 separate sub-blocks.Dueto leakage through part of the block joints,work was needed to stop thisflow.So as that this project, in 1995, was proceeded to overcome this problem.The polyurethane resin injection was selected as the approach for this project.The injection work was executed focused on the block construction joints, upstream and downstream surface respectively. After the injection works,the repaired joints performed well as predicted and leakages were sealed.