In 2021, the Chongqing Natural History Museum, in collaboration with the Chongqing Institute of Cultural Relics and Archaeology and the Institute of Vertebrate Paleontology and Paleoanthropology, conducted a systematic excavation at the Xiniudong site in Fengdu County, Chongqing. Among the small mammal assemblages recovered from this site, Pteromyinae fossils were notably abundant. Comparative morphological analyses identified these fossils as belonging to four genera and five species: Trogopterus xanthipes, Belomys pearsonii, Pteromys volans, Petaurista alborufus, and one indeterminate species of the genus Petaurista (Petaurista sp.).Faunal composition analysis shows that fossil specimens of P. volans account for approximately 21.8% of the total Pteromyinae fossils, and those of B. pearsonii account for about 65.6%. The two species were absolutely dominant among the Pteromyinae living in the same period, indicating that the habitat and ecological environment at that time were suitable for the prosperous population development of both species. The P. volans mainly inhabits coniferous forests and mixed coniferous-broadleaved forests, while B. pearsonii is mainly distributed in subtropical broad-leaved forests. This difference in habitat preference suggests that broad-leaved forests and mixed coniferous and broad-leaved forests at least existed around the Xiniudong site during the period 41 000～45 000 years ago. The research results not only improve the mammalian faunal database of the Late Pleistocene in southern China, but also provide important biostratigraphic evidence for reconstructing the paleoecological pattern of the Three Gorges region during this period.