The bedding slope landslide is the main type among the landslides triggered by Wenchuan earthquake. Ancient seismic landslides of the bedding slope are worthy for investigation and study as they were large scales and made serious destruction. Based on the field investigation, the characteristics of Mahu landslide group has been revealed: (1) Five divisions can be identified according to the composition of the accumulation, weathering degree of the gravels. They were formed in different seismic events. (2) Five stages can be recognized, they are early Pleistocene, early middle Pleistocene, late middle Pleistocene, early Pleistocene and Holocene. (3) As the seepage deformation tends to be stable, the dam lake have lasted for thousands of years.