Abstract: Soil plays an important role in the land surface environment and is the basic component of terrestrial ecosystem. The physical and chemical properties of soil will affect the energy transfer and material exchange between organisms and the environment, and also limit the composition of plant communities and the stability of ecosystems. Starting from introducing the fragile ecological situation of Qinghai-Xizang Plateau, this paper expound the interaction between soil physical and chemical properties and ecological environment around soil organic matter, soil temperature and humidity and soil nitrogen, phosphorus and potassium, analyzed the soil physical and chemical characteristics of different ecosystems（grassland ecosystem, wetland ecosystem and cold desert ecosystem）, and proposed some countermeasures for the problems existing in fragile ecosystems.