Abstract: (1) The community of Castanopsis platyacantha-Schima sinensis is one of the typical types of the evergreen broadleaved forest vegetation in the midsub-tropical mountainous region of West China.(2) This primary forest community distributes in an altitudinal range from 1200m to about 1600m on Emei Mountain (N29˚31′—38′, E103˚15′—28′) where the mean annual rainfall (1951—1983) was 1000mm. Ten plots (of 0.4ha)at altitudes from 1230m to 1580m on the western slope of this mountain were studied in detail.(3) There is a floristic composition with about 61 families, 116 genera and 171 species in the plots, which is interesting to note that the tropical types of family and genus occupy a noticeable position both by their numbers and Importance Values (Ⅳ.). The diversity was computed by Simpson index, shannon-Wiener index, PIE and Evenness, and the higher results are 9.71, 4.11, 0.89 and 76.57.(4) The physiognomy of the community is dominated by both the lifeform (Raunkiaer′s system, 1967) with evergreen Microphanerphytes-Moaophanerphytes and the leave characters with Microphylls-Mesophylls, Corlaceous-Thick coriaceous textures, Single form and Entire margin. The most significant characters are that there is an abundance of Liana and Epiphytes in this community.(5) The complex structure has a distinct vertical stratification which can be divided into five strata or layers (Richards, 1952). The tree stratum can be divided into three sublayers A, B and C further, and the shrub layer can be divided into two sublayers. Some higher individuals of the shrub species enter to C sublayer of the tree stratum. Both Castanopsis platyacantha and Schima sinensis occupy much higher IVs than any other tree species and become the constructive species and the dominant species of the community, which is named by.(6) The age-structures of the main tree populations are at increasing and steady states Therefore, this community has a higher ecological stability and its dynamic status is a type of progressive succession. In the other aspect, there are indications that the competitive substitute and exotic species succession coexist in the community. Moreover, other questions, e. g. patterns of the populations, similarities of the studied quadrats and associations between the species, were discussed in this paper.(7) This area is exactly located at the ecotope of rainfall peak not only on the horizonal belt but on the vertical belt of this mountain. It is the most important ecological reason why there are so many dramatic characters of the subtropical rain-forest vegetation in the southern subtropical areas of China remaining in the community of Castanopsis platyacantha-Schima sinensis on Emei Mountain.