In 2000, 2002, and 2006 we captured small mammals in the Liangshan Mountains, Mabian Dafengding National Nature Reserve and Meigu Dafengding National Nature Reserve, Sichuan Province, China. Among the collected specimens we identified a new species of the genus Proedromys. Its identifying characteristics are its relatively long tail, broad upper incisors without grooves, comparatively short lower incisors, and features of the molar teeth. The glans penis of the new species also is distinctive, the proximal and distal bacula are bony, whereas the lateral bacula are only slightly ossified. The proximal baculum is flask-shaped, the distal baculum is cap-shaped, and the lateral bacula are stick-shaped. This species is associated with high-elevation spruce–fir forest habitat, an unusual setting for Proedromys across its geographic range.