Abstract：On the basis of the detailed geology surveying and testing，many exploration data are analyzed for Baiyi¢an Landslide in the area of Three Gorges Reservoir，Yangtze River，China. At the aspects of engineering geology and hydrogeology analysis，the disintegration evolution and development trends of the landslide are revealed. According to the relationships of Quaternary sediments and the ages，the traces of deformation and failure of the special stratum，and the geological events，the historic geology of Baiyi¢an Landslide is analyzed and the evolutional history of Baiyi¢an Landslide is studied. It is shown that Baiyi¢an Landslide is stable as a whole，but instable locally. The small or medium landslides may result in disassembly of Baiyi¢an Landslide. Debris flow may be locally triggered by intense rainfall. The dangerous parts of Baiyi¢an Landslide must be reinforced. The terraces in the front of Baiyi¢an Landslide are in favor of stability and it should be protected for reservoir operation. Small or medium landslides and debris flow are the main geologic hazards of Baiyi¢an Landslide area. During the long-term evolution of large ancient landslides，some geologic events happen occasionally，as a result that some geologic traces remain inside or on the landslides. By analyzing the geologic events and phenomena，the development trend of the landslide can be examined. It is necessary that the detailed geologic investigation should be carried out so that the minute and unobvious trails can be found out. By the combination analysis of historic geology with engineering geology of ancient landslide，evolution and characteristics of large ancient landslide can be revealed under the various geologic environmental conditions. The method can be used to qualitatively realize the stages of evolution of landslide and to evaluate landslide stability and its development trend.
