Abstract: During the construction period of the Three Gorges Project (TGP) shiplift dam block,the horizontal and vertical displacement of its foundation gallery and its foundation deformation undergo an unusual process. Based on the topography and geology conditions of the foundation and the structure characteristics of the dam block, the analysis of the unusual process is made by use of the monitoring data in this paper. As a result, the working behavior of the TGP shiplift dam block is appraised.?