Abstract:The upper or alpine timberline(AT) can be either a transitional zone or an abrupt border between continuous forest and herb, shrub and high mountain cushion communities. At present, Although there have been more reports on their positions and dynamics which may be controlled by limitations imposed by abiotic environmental conditions such as low temperature, aridity, wind and snow on the production of viable pollen, viable seeds, seed germination and the survival of saplings and adults, but there is lack of information to understand the effects each other between changing vegetations and their soil properties in this geographical region. Therefore, in a short distance, the physical, chemical and biological properties of the soil mainly taken place in residual deposits in subalpine timberline ecotone, scree meadow and fir forest, were investigated in Wanglang National Nature Reserve in this paper. The results show that from scree meadow to timberline ecotone then to fir forest, with the changement of vegetation some physical structure parameters such as the content of scree, silt, clay and physical clay, aggregate degree, structure coefficient, and some chemical parameters such as the content of soil water, hydrolyzed acid, organic matter, total P, total K, available N, available P and soluble K, exchangeable base content, cation exchangeable capacity content, base saturation percentage and so on in the topsoil(0-30 cm) all were increasing slowly, showing that the soil physical structure and chemical properties were improved but developing slowly on the residual deposits. Furthermore, in the topsoil of the subalpine timberline ecotone, the microbe quantities of bacteria, fungi and actinomyces, enzymatic activities of acid phosphatases, neutra phosphatase, urease, invertase, catalase and polyphenol oxidase were highest among three vegetations, implying that as a ecotone, the soil biological and chemical activities in subalpine timberline ecotone were more active than them in the adjacent vegetations.