Abstract: For the purpose of environment protection and practical agricultural production,the maximum admissible load of livestock manure of the farmland in the watershed of Miyun Reservoir was calculated based on the principles of soil-plant nutrition and the theory of scientific fertilization.By comparing the actual load of livestock manure with the maximum admissible load,environmental risk of livestock in each community within the watershed was evaluated.The results indicate that the pollution caused by livestock excrements threatens water quality of the watershed with different extents.Gubeikou,Shicheng and Fanzipai are exposed to the highest risk,and then Beizhuang follows.