Abstract: Zipingpu Concrete-Faced Rockfill Dam, which was subjected to significant local damage during "5.12" Wenchuan Earthquake, which is the first concrete-faced rockfill dam of more than one hundred meters in height encountering strong earthquake in the world. Based on the finite element data smoothing method, the permanent strain at a typical cross-section of the dam is obtained by processing the monitored displacement data. The positions of the dam settlement and rockfill dilatancy and the causes are analyzed according to the section permanent strain. The results show that the maximum settlement ratio of the dam approximately occurs at 2/3 of the dam height. The dilatancy occurs from the dam crest to 25～30 m in the upstream and downstream slope. The excessive permanent shear strain during the earthquake is the immediate cause for dislocation of the horizontal construction joints in the face slabs.