Abstract: The niche overlaps of 54 main woody species in 39 sites in Baiyun Mountain of Lishui, Zhejiang Province were calculated by Wang's equation, two dimensional scatter plot of principal axes analysis and the minimal spanning tree on the basis of niche overlaps were drawn. Both the ordination plot and the minimal spanning tree revealed higher ecological similiarities among Pinus massoniana, Schima superba, Loropetalum chinensis, Castanopsis eyrei, Rhododendron ovatum,Castanopsis sclerophylla, Quercus glandulifera var. brevipetiolata, Castanea henryi and Lindera aggregata and those among Litsea cubeba, Castaneia mollissima,Nyssa sinensis,Clerodendrum cyrtophyllum,Prunus serrulata var. pubescens and Taxus mairei. The niche width of the 54 woody species was also calculated by the modified equation put forward by Levins. The 54 woody species could be divided into five ecological groups according to their niche widths. It was found that Pinus massoniana, Loropetalum chinensis, Schima superba, Castanea henryi, Castanopsis eyrei, and Eurya muricata had wider niche breadth.The relationship between niche width (B) with the number of the woody species (N) could be described by N=18.333 e^{-4.4109 B}, R²=0.9467,α<0.01), indicating that the number of woody species decline exponentially with the breadth of the niche in Baiyun Mountains.