Abstract: Based on studying the development of fault and interlayer shear zone in the dam region, it is suggested that the formation of these two kinds of structures plane was controlled by tectonic and epigenetic reworking. This paper analyzes district structure characteristic and strata lithology first, discusses structure origin of the plane, and builds up its structure origin pattern. The fault structure plane belongs to the overthrust pattern on the foundation of conjugate shear outbursts, and the interlayer shear zone belongs to the surge pattern of vertical camber beam. Based on the analysis of epigenetic reworking of the structure plane, the character and state changing law of structure plane is revealed. The fault structure plane displays thickness, material type and character segmentation.