Abstract: The niche breadths and overlaps of 8 main tree species, 18 main shrub species and 42 main herb species in the Shenweigou of Guandi Mountain were measured using the formulas proposed by Shannon-Wiener and Petraitis, and the relationships between niche breadth and niche overlap were discussed in this paper. The results show that the niche breadths of Populus davidiana, Picea meyeri and Betula platyphylla in tree layer and those of Sambucus williamsii, Viburnum shensianum and Spiraea pubescens in shrub layer and those of Dianthus chinensis, Polygonatum verticillatum and Saussurea amara in herb layer were greater, which was related with their own characteristics and the capability of adapting environment.The greater the niche breadths of species was, the more intense the species was adapted to the environment. The niche overlaps among the species with the same or similar environment requirements were great, while those between the species with broad niche breadth and other species were much greater.