Abstract: Species diversity,floristic components,and age structure of the dominant species population of the Machilus chekiangensis community in Dadongshan,Nanling National Nature Reserve,Guangdong Province were studied by using the method of plots for vegetation survey.Results showed:(1) There were 169 vascular species belonging to 119 genera and 73 families in an area of 1600 m².The families which have more in the amount of the community included Lauraceae,Rosaceae,Theaceae,Fagaceae and Ericaceae.The floristic elements of family and genera were mainly Tropical distributed,74.51% and 70.10% respectively,and Temperate element is 23.53% and 33.64% respectively.(2) Analysis on age structure of Machilus chekiangensis,the dominant species in the community,indicated that young trees were the main component,while Castanopsis fabri,Pinus massoniana,Schima superba et al.were subdominant species in the tree-layer.(3) Vertical structure of the community was composed of arbor,shrub and herb layers,among which shrub layer had the most species.Analysis on four species diversity indices showed different trend curves,in which Simpson index:shrub layer>tree layer=herb layer;Shannon-Wiener index:shrub layer>tree layer>herb layer;Margalef richness index:shrub layer>tree layer>herb layer;and Pielou evenness index:tree layer>shrub layer>herb layer.