The soils characteristics and impacts of human disturbances on the ecosystem of the Shangri-La Canyon were studied.The results show that 9 soils are distributed in clearly vertical zonation from 2,000m to 5,545m in altitude.The ratio of C/N in the soils is high,indicating that in the Shangri-la Canyon the soil formation processes were dominated with accumulation of organic matter.The average content of organic matter in the natural soil under forests is 100 g/kg,but is reduced to 28.7 g/kg after the soil has been cultivated as sloping cropland and to 22,3 g/kg in deserted farmland,which is evidence of soil degradation under the impact of human activities.On mire soil,harmful and poisonous weeds,such as Euphorbia jolkinii and Artemisia hedinii representative of soil degradation,are intruding into the meadow as a result of over-grazing.Soil degradation also occurs under the impact of nature disturbance such as forest fire.Moreover,the soil in the Shangri-la Canyon is higher than the soils in the other mountains areas in Yunnan,but cold weather limits the soil productivity and plant growth.Once the vegetation is destroyed,it is very hard to restore it.Thus the loss of forests with their function of conserving of water supply threatens the natural eco-environment in the vicinity and the down-streams of the Yangtze River catchment.