Abstract: This paper deals with the phytosociological characters of the Wumon-fir (Abies georgei var. smithii) forest, which has been remained in the Wumon mountain range of Yunnan. Only a small area of this forest is now disperse over there, located 3100--3900m. in altitude. It is the only subalpine coniferous forest found in the north part of the middle Yunnan Plateau, and is considered as an important component of the vertical vegetation spectrum in that region. The natural community is a uni-dominant forest, dominated by the Wumon-fir. In this forest, a few Tsuga dumosa is found occasionally. Some species of Sorbus, Viburnum, Salix, Acanthopanax, Hydrangea, Ilex, Rhododendron and others are seen in the understory. The shrub layer is mainly consisted of the subalpine bamboo Sinarundinaria, and there are many species in herb layer. The great majority of the floristic component belongs to Sino-himalayan. The phytosociological characters of this fir forest are very similar to the north-west one of Yunnan, but the tree layer lacks species of Picea and Larix. Therefore it may be stated that this forest is a south-east boundary type of the vegetation in the area among the north-west Yunnan, the south-west Sichuan and the south-east Tibet. It has arrived at the distributional limitation of that area. This forest is the remainder of the natural history, and under the men’s activities, its area has been become narrow and narrow. Based on this reason, it should be protected strictly. If so, it will bring in very active role about great changes of agriculture, forestry, pasturage in the Wumon mountain range.