Abstract: Animal husbandry exerted very important effects on meat product supply, people’s life improvement and farmer’s income increase, but the nitrogen of livestock manure polluted the environment, so it was important to strengthen the research about nitrogen pollution and environmental cost of livestock manure. Taking the Dongting lake area in Hunan province as an example, this paper assessed the nitrogen pollution and environmental cost from farmland, water body and atmosphere in this area. The results showed that in 2006, the nitrogen nutrient of livestock manure in Dongting lake area was 18.99×104 t，the environmental cost of nitrogen pollution in livestock manure was 8.77×108 RMB, the polluted environment cost of farmland, water body and atmosphere was 2.32×108 RMB, 4.81×108 RMB and 1.64×108 RMB, respectively. The nitrogen pollution of livestock manure can not be ignored.