Abstract: The mammalian fossils were collected from the cave deposits of Wushan county, Sichuan Province, by a field team of IVPP and Chongqing Shi Museum in the summer of 1984. The list of the mammalian fossils, including 10 species, is given at p. 82 in the Chinese text.In this paper some problems concerning the karst cave are discussed on the basis of the palaeontological materials. The fossils, though insufficient, were discovered for the first time in Eastern Sichuan. The Ailuropoda microta, Hyaena licenti Machairodontinae, Chaliotheriidae, Tapirus cf. peii, Equus cf. yunnanensis are similar to those species or family found in the Liucheng Gegantopithecus cave, and some other species are mainly the elements about the Ailuropoda——stegodon fauna in South China.All things considered, such as stratigraphical position and fossil assemblage, the karst fissures in the Shanyuan stage should be dated Late Miocene-Pliocene, the fossil——bearing bed is Early Pleistocene-Middle Pleistocene.Several characters of the new mammal fauna and cave deposits in Yen-chingkou are generally described here. It shows that the new fauna is different from the old one, because the new fauna is not only clear in Iocality. butalso clear bones——bearing bed. To sum up, the discovery of the new sitewould help a lot in the study of the geological age of Yenchingkou fauna.The study of these new mammal fossils helps to understand the geological development of the Changjiang River and the formation of Three Gorges (Changjiang River). Through the present discovery, we analyse that it is perhaps the most probable, for to find early human fossil in the Shangyuan stage and Gigantopithecus in the north of Changjiang River.