Abstract: Prosiphneus Teilhard de Chardin, 1926 is the most primitive genus of the Siphneidae Leroy, 1941 and one of the most important rodent taxa of East Asian Hipparion Fauna. Prosiphneus licenti from Qingyang, Gansu had been regarded as the earliest species before the early late Miocene “Pr. inexpectatus” was found from Amuwusu, Nei Mongol by Zhou Zheng in 1983. However, the latter species name is not valid because it has not been published, though cited by Zheng in 1994, and the specimens are lost. Fortunately , more materials were collected from the same locality by Qiu Zhanxiang in 1986 and Qiu Zhuding in 1995～1996. In 2000, Dr. Hao Qingzhen collected some isolated teeth of Prosiphneus from different layers of a section located 27 km northwest of Qinan town. These fossils were listed as Prosiphneus n. sp. 2, Prosiphneus n. sp. 1, and Pr. licenti respectively without description (Guo et al., 2002). Based on detailed description of the above materials, the relationships among Prosiphneus species and the origin of siphneids are discussed herein.