Abstract: The study of rodents was Considered out in 1981 in Mountain West Tian-mu, Zhejiang Province. Four working sites were set up at different altitudes in the mountain range. Fourteen species of Rodentia were captured. Rattus niviventer confucianus, Apodemus sylvatic draco, and Eothenomys mslanogastar colurnus were the dominant species, accounting for 76.89% of the total specimens.It was observed that the number of species decreased as the altitude increased. The species and their relative densities were different in every working site. Excluding house mice and squirrels, the Rodents could be divided into three ecological groups according to their distribution and habitat.The seasonal variation cf the animals' numbers might be affected by the factors of reproductive action, vegetation, elevation, precipitation and temperature. Peaks in the fluctuation curve appeared in March, May and October-November respectively, and the lowest was in August. The number of rodents was higher at the top than at the foot of the mountain from May to October, but it was just the opposite in other months.