Abstract: Based on the detailed geologic survey and drilling data, the basic characteristics of the Dacun landslides are elaborated, including space distribution, material composition, slip band and bed features. The genesis of the Dacun ancient landslide is analyzed and discussed, and then, the internal and external factors affecting the stability of the landslide are combined, and its reviving mechanism is discussed. Finally, we evaluate the stability of the Dacun landslides. The results show that the continuous erosion of the Sanyu river and storm are the direct cause of the ancient landslide and its modern reviving.