Numerous remains of a bamboo rat from the Early Pleistocene of Renzidong Cave are described systematically. The morphological characters of the remains indicate that they are assignable to a new species of Rhizomys, which is named R. fanchangensis here. Rhizomys is an extant genus, but the new species is extinct and shows such primitive characters as being small-sized and bearing brachydont molars as a species of Rhizomys. It is chronologically the oldest one among the species of Rhizomys. Thus, the new species is important for bridging the Pliocene species of the ancestral genus, Brachyrhizomys, and Rhizomys species from the later stages of the Quaternary, chronologically and morphologically. Additionally, in this paper, we follow the chronological division of the Pliocene and Pleistocene generally adopted among Chinese geologist, in which their boundary lies at the Matuyama/Gauss geomagnetic boundary.